Search Results (260)

Background: Epicardial adipose tissue (EAT) is a visceral fat depot surrounding the myocardium. It contributes to coronary artery disease (CAD) through local inflammation, while its metabolic activity, including the expression of uncoupling protein-1 (UCP-1) and incretin receptors (GLP-1R, GIPR), may exert protective effects. The relationship between EAT immunohistochemical features and imaging-derived volume remains unclear. Methods: We prospectively studied 50 patients undergoing cardiac surgery: 25 with CAD undergoing coronary artery bypass grafting and 25 without CAD undergoing valve replacement. EAT samples were immunohistochemically stained for CD3, CD68, MPO, UCP-1, GLP-1R, and GIPR. Preoperative CT was used to quantify EAT volume. Results: Patients with CAD more frequently had higher CD3 immunopositivity compared to the control group (84.0 vs. 58.3%, p = 0.047), with no difference in MPO and CD68 immunoexpression. UCP-1 expression was elevated in CAD patients (p = 0.004), whereas GLP-1R and GIPR immunopositivity were similar. EAT volume did not differ between CAD and non-CAD patients (102.87 cm³ vs. 99.38 cm³, p = 0.964) but correlated modestly with BMI (r_s = 0.325, p = 0.021). UCP-1 and GLP-1R immunopositivity, as well as larger LVEDD (left ventricular end-diastolic diameter), were positively associated with greater EAT volume. Conclusions: EAT in CAD exhibits increased T-cell infiltration and elevated UCP-1 expression, indicating an inflammatory yet metabolically active profile. Larger EAT volume was associated with UCP-1 and GLP-1R expression, underscoring the immunometabolic role of EAT in CAD. Full article

Background: Dalbavancin and oritavancin are long-acting lipoglycopeptides increasingly used off-label for a variety of Gram-positive infections. While their efficacy has been described in osteomyelitis, bacteremia, and infective endocarditis, evidence specifically addressing cardiovascular prosthetic infections such as prosthetic valve endocarditis (PVE), cardiac implantable electronic device (CIED) infections, left ventricular assist device infections (LVAD), and prosthetic vascular graft infections (PVGI) remains limited. These conditions are particularly challenging due to biofilm formation, difficulties in achieving surgical source control, and the frequent need for prolonged or suppressive therapy. Objectives: This systematic review aimed to summarize the available literature on the use of dalbavancin and oritavancin in cardiovascular prosthetic infections, with a focus on therapeutic strategies, clinical outcomes, and safety. Methods: We performed a systematic search of PubMed, Embase, Scopus, and Cochrane Library up to 24 June 2025 in accordance with PRISMA guidelines. Eligible studies included adults treated with dalbavancin or oritavancin for cardiovascular prosthetic infections. Data on study characteristics, population demographics, causative pathogens, and microbiological profiles, antibiotic regimens, treatment duration, use of therapeutic drug monitoring (TDM), indication or non-indication for chronic suppressive therapy, adverse events, clinical outcomes, and clinical efficacy were extracted. Results: Twenty studies comprising 113 patients were identified, of whom 111 received dalbavancin and 2 oritavancin. The main infections were PVE, CIED, LVAD, and PVGI. Dalbavancin was most effective as consolidation therapy after surgery or device removal, with high cure rates. Prolonged regimens were used as bridging or in partially treated cases, sometimes supported by TDM or PET/CT. Chronic suppressive therapy, mainly for LVAD and PVGI infections, achieved variable outcomes with relapses in about one fifth of patients. Adverse events were infrequent and generally mild. Conclusions: The included studies were highly diverse, conducted in various settings and with different objectives. Eight of the twenty included studies were single case reports on dalbavancin and oritavancin, highlighting the predominance of individual case descriptions in the available literature. Long-acting lipoglycopeptides may represent a valuable option for cardiovascular prosthetic infections. Their role appears most favorable as consolidation after adequate source control, while chronic suppressive use showed heterogeneous outcomes. This systematic review was registered on Open Science Framework. This work was supported by grants from the Italian Ministry of Health through Ricerca Corrente, Linea 3, Progetto 3. Full article

A collaborative control strategy combining the hyperbolic sine-cosine optimization (SCHO) algorithm with fuzzy adaptive linear active disturbance rejection control is proposed to address the nonlinearity and uncertainties in the hydraulic position servo system of shock absorber test benches. First, based on the dynamic characteristics of the shock absorber fatigue test bench and the tested shock absorber, a linearized model of the valve-controlled hydraulic cylinder and its load was established. The coupling mechanism of system parameter perturbation and disturbance was also analyzed. A third-order LADRC (Linear Active Disturbance Rejection Control) was designed considering the linear model characteristics of the test bench hydraulic servo system model to quickly estimate internal system disturbances and perform real-time compensation. Secondly, a multi-objective optimization function was constructed by integrating system performance indicators and incorporating controller and observer bandwidths into the optimization objectives. The SCHO algorithm was used for the global search and optimization of key LADRC parameters. To enhance the controller’s adaptive capability of modeling uncertainties and external disturbances, a fuzzy adaptive module was introduced to adjust control gains online according to errors and their rates of change, further improving system robustness and dynamic performance. The results show that compared with traditional PID, under different working conditions, the proposed method reduced the maximum tracking error, overshoot, and system response time by an average of 45%, from 15% to 5%, and by approximately 30%, respectively. Meanwhile, the parameter combination obtained via SCHO effectively avoids the limitations of manual parameter tuning, significantly improving control accuracy and energy utilization. The simulation results indicate that this method can significantly enhance position-tracking accuracy compared with traditional LADRC, providing an effective solution for position-tracking control in hydraulic servo testing systems. Full article

Structural heart interventions require precise navigation through tortuous and dynamic cardiac anatomies. However, current guide sheaths often lack sufficient maneuverability for positioning additional catheters. To address these limitations, this paper presents the design and evaluation of a robotic guide sheath with a dual-bendable, compressible tip. The sheath is capable of navigating complex cardiac anatomies for multiple valve interventions. The system consists of a soft continuum sheath tip driven by tendons, a laser-cut compact motorized actuation bed, and a joystick-controlled tendon actuation mechanism. A constant-curvature kinematic model maps actuation inputs to tip bending in 3D, while a custom software interface enables real-time control. Mechanical evaluation (tension, maximum bending, and contraction tests) demonstrated low actuation tension requirements (0.78 N), a wide bending range (from 80° to 90°), and promising tip compressibility (average 5 mm). Trajectory-following tests showed good accuracy, with an average error of 3.34 mm. Catheter guidance trials further validated the sheath’s ability to navigate to the right atrium and guide additional catheters effectively. This work presents a proof-of-concept robotic guide sheath with enhanced maneuverability and adaptability, establishing a foundation for future integration of sensing, automation, and clinical applications. Full article

Control valves are widely applied in nuclear power, offshore oil/gas extraction, and chemical engineering, but suffer from issues like pressure oscillation, flow control accuracy degradation, and motor overload due to unstable fluid loads (e.g., nuclear reactions in power plants and complex marine climates). This paper proposes a dual-motor redundant compensation method to address these challenges. The core lies in a control strategy where a single main motor drives the valve under normal conditions, while a redundant motor intervenes when load torque exceeds a preset threshold—calculated via the valve core’s fluid load model. By introducing excess load torque as positive feedback to the current loop, the method coordinates torque output between the two motors. AMESim and Matlab/Simulink joint simulations compare single-motor non-compensation, single-motor compensation, and dual-motor schemes. Results show that under inlet pressure step changes, the dual-motor compensation scheme shortens the stabilization time of the valve’s controlled variable by 40%, reduces overshoot by 65%, and decreases motor torque fluctuation by 50%. This redundant design enhances fault tolerance, providing a novel approach for reliability enhancement of deep-sea oil/gas control valves. Full article

Background: The mitral valve apparatus is a complex system that requires sufficient function of all involved structures. Previous studies have demonstrated that ventricular remodeling can cause displacement of subannular structures, including the papillary muscles, which in turn promotes the development of mitral regurgitation. Furthermore, in such cases, annuloplasty alone is often insufficient to restore optimal valve function. Instead, additional reconstruction of the subannular apparatus is associated with improved clinical outcomes. Our study aimed to analyze the topography of the papillary muscles in the mitral valve complex and their relevance for mitral valve function. Methods: In 148 patients who underwent both cardiac computed tomography (CT) and echocardiography, the position of the papillary muscles within the left ventricle was assessed. CT scans were evaluated in end-diastolic four-chamber view, two-chamber view, and short-axis view. CT analysis involved determining the position of the papillary muscles based on a modified left ventricular segmentation scheme, which subdivided the original segments into “a” and “b” subsegments in a counterclockwise manner. Furthermore, the midventricular diameter, ventricular length, as well as the angle between the papillary muscle (PM) and the left ventricular wall, were measured. Comorbidities were assessed. The presence of mitral regurgitation (MR) and ejection fraction was determined based on echocardiographic data. Echocardiography was conducted either as part of initial cardiological assessments or during follow-up examinations. For detailed statistical analysis, the patients were divided into the following groups: control group, MR-only group, coronary heart disease (CHD)-only group, and combined CHD and MR subgroup. Results: Mitral regurgitation was significantly correlated with age (p < 0.001) and hypertension (r = 0.1900, p = 0.0208), and in the MR-only subgroup, additionally with atrial fibrillation (r = 0.2426, p = 0.0462). The length (p < 0.001) and internal diameter (p < 0.001) of the left ventricle were significantly larger in men than in women. Different positions of the papillary muscles were identified. Segment 7a was significantly correlated with MR in the combined CHD and MR subgroup. In normal-sized ventricles, patients with MR and papillary muscle in 12a (p = 0.0095) or 10a (p = 0.0460) showed a significantly larger angle than patients without MR (overall dataset). Conclusions: Assessment of papillary muscle position is essential in diagnosing mitral regurgitation and should guide the consideration of subannular repair during surgical treatment. Full article

The present article compares the Proportional Directional Control Valve (PDCV) and the Stepper Motor-Driven Orbitrol Valve (SMDOV) coupled to the steering system of the articulated steered vehicles. Simulation models of both valve coupled steering systems are developed in a MATLAB (r2019b) environment, and results are well validated with the experimental data. Comparison analysis is performed between the PDCV and SMDOV steering systems by controlling the desired position demand using a conventional PID controller. From the comparative study, it is observed that the SMDOV provides almost 50% energy reduction, but the valve response is low compared to PDCV. However, the steering response provided by the SMDOV is quite enough for performing steering operations in mining conditions. Overall, the orbitrol valve-assisted steering system offers more efficient and smooth steering than the PDCV valve. The future work of the present study extends to the development of autonomous steering operation using an orbitrol valve-operated articulated steering system. Full article

Electro-hydraulic proportional multi-way valves are widely used in construction machinery and equipment, and their performance directly affects the operation performance of construction machinery and equipment. In this paper, an electro-hydraulic proportional multi-way valve was taken as the research object, and the precise control of the position of the spool of electro-hydraulic proportional multi-way valves under multi-source disturbances was studied. A mathematical model of the electro-hydraulic proportional multi-way valve was established to analyze the influence of hardware controller parameters on the control current. A proportional multi-way valve expansion state observer was established to observe the changes in internal and external multi-source disturbances, and a sliding mode controller was used to compensate for the influence of these disturbances on the position control accuracy of the valve spool of proportional multi-way valves. Compared with the PID control method, the results show that, when using the control method proposed in this paper, the reduction in the step response time and improvement in pressure control accuracy for the pilot proportional reducing pressure valve were maximally 44.4% and 0.61%, respectively; the reduction in the step response time and improvement in control accuracy for the spool of the pilot proportional multi-way valve were maximally 69.48% and 61.74%, respectively. The research results in this paper can help to improve the performance and multi-condition adaptability of electro-hydraulic proportional multi-way valves. Full article

This study focuses on the optimization of valve assemblies in downhole rod pumping units (DRPUs), which remain the predominant artificial lift technology in oil production worldwide. The research addresses the critical issue of premature failures in DRPUs caused by leakage in valve pairs, i.e., a problem that accounts for approximately 15% of all failures, as identified in a statistical analysis of the 2022 operational data from the Uzen oilfield in Kazakhstan. The leakage is primarily attributed to the accumulation of mechanical impurities and paraffin deposits between the valve ball and seat, leading to concentrated surface wear and compromised sealing. To mitigate this issue, a novel valve assembly design was developed featuring a flow turbulizer positioned beneath the valve seat. The turbulizer generates controlled vortex motion in the fluid flow, which increases the rotational frequency of the valve ball during operation. This motion promotes more uniform wear across the contact surfaces and reduces the risk of localized degradation. The turbulizers were manufactured using additive FDM technology, and several design variants were tested in a full-scale laboratory setup simulating downhole conditions. Experimental results revealed that the most effective configuration was a spiral plate turbulizer with a 7.5 mm width, installed without axis deviation from the vertical, which achieved the highest ball rotation frequency and enhanced lapping effect between the ball and the seat. Subsequent field trials using valves with duralumin-based turbulizers demonstrated increased operational lifespans compared to standard valves, confirming the viability of the proposed solution. However, cases of abrasive wear were observed under conditions of high mechanical impurity concentration, indicating the need for more durable materials. To address this, the study recommends transitioning to 316 L stainless steel for turbulizer fabrication due to its superior tensile strength, corrosion resistance, and wear resistance. Implementing this design improvement can significantly reduce maintenance intervals, improve pump reliability, and lower operating costs in mature oilfields with high water cut and solid content. The findings of this research contribute to the broader efforts in petroleum engineering to enhance the longevity and performance of artificial lift systems through targeted mechanical design improvements and material innovation. Full article

This paper presents some of the most significant findings in the design of a hydraulic servomechanism for flight controls, which were primarily achieved by the first author during his activity in an aviation institute. These results are grouped into four main topics. The first one outlines a classical theory, from the 1950s–1970s, of the analysis of nonlinear automatic systems and namely the issue of absolute stability. The uninformed public may be misled by the adjective “absolute”. This is not a “maximalist” solution of stability but rather highlights in the system of equations a nonlinear function that describes, for the case of hydraulic servomechanisms, the flow-control dependence in the distributor spool. This function is odd, and it is therefore located in quadrants 1 and 3. The decision regarding stability is made within the so-called Lurie problem and is materialized by a matrix inequality, called the Lefschetz condition, which must be satisfied by the parameters of the electrohydraulic servomechanism and also by the components of the control feedback vector. Another approach starts from a classical theorem of V. M. Popov, extended in a stochastic framework by T. Morozan and I. Ursu, which ends with the description of the local and global spool valve flow-control characteristics that ensure stability in the large with respect to bounded perturbations for the mechano-hydraulic servomechanism. We add that a conjecture regarding the more pronounced flexibility of mathematical models in relation to mathematical instruments (theories) was used. Furthermore, the second topic concerns, the importance of the impedance characteristic of the mechano-hydraulic servomechanism in preventing flutter of the flight controls is emphasized. Impedance, also called dynamic stiffness, is defined as the ratio, in a dynamic regime, between the output exerted force (at the actuator rod of the servomechanism) and the displacement induced by this force under the assumption of a blocked input. It is demonstrated in the paper that there are two forms of the impedance function: one that favors the appearance of flutter and another that allows for flutter damping. It is interesting to note that these theoretical considerations were established in the institute’s reports some time before their introduction in the Aviation Regulation AvP.970. However, it was precisely the absence of the impedance criterion in the regulation at the appropriate time that ultimately led, by chance or not, to a disaster: the crash of a prototype due to tailplane flutter. A third topic shows how an important problem in the theory of automatic systems of the 1970s–1980s, namely the robust synthesis of the servomechanism, is formulated, applied and solved in the case of an electrohydraulic servomechanism. In general, the solution of a robust servomechanism problem consists of two distinct components: a servo-compensator, in fact an internal model of the exogenous dynamics, and a stabilizing compensator. These components are adapted in the case of an electrohydraulic servomechanism. In addition to the classical case mentioned above, a synthesis problem of an anti-windup (anti-saturation) compensator is formulated and solved. The fourth topic, and the last one presented in detail, is the synthesis of a fuzzy supervised neurocontrol (FSNC) for the position tracking of an electrohydraulic servomechanism, with experimental validation, in the laboratory, of this control law. The neurocontrol module is designed using a single-layered perceptron architecture. Neurocontrol is in principle optimal, but it is not free from saturation. To this end, in order to counteract saturation, a Mamdani-type fuzzy logic was developed, which takes control when neurocontrol has saturated. It returns to neurocontrol when it returns to normal, respectively, when saturation is eliminated. What distinguishes this FSNC law is its simplicity and efficiency and especially the fact that against quite a few opponents in the field, it still works very well on quite complicated physical systems. Finally, a brief section reviews some recent works by the authors, in which current approaches to hydraulic servomechanisms are presented: the backstepping control synthesis technique, input delay treated with Lyapunov–Krasovskii functionals, and critical stability treated with Lyapunov–Malkin theory. Full article

Fuel electro-hydraulic servo valves are core components in the fuel control system of aero-engines, and their performance directly affects thrust regulation and power output precision. Due to the combustibility of the working medium in fuel systems and the lack of effective circulation filtration, the retention of micron-sized particles within the valve gap can lead to valve spool jamming, which is a critical reliability issue. This study, based on fractal theory and the liquid–solid two-phase flow model, proposes a parametric model for non-ideal surface valve gaps and analyzes the dynamics of particles subjected to drag, lift, and buoyant forces on rough surfaces. By numerically analyzing flow field models with different roughness levels and comparing them with an ideal smooth gap model, the migration characteristics of particles were studied. To verify the accuracy of the model, an upscaled experimental setup was built based on similarity theory, and PIV experiments were conducted for validation. Experimental results show that the particle release position and valve surface roughness significantly affect particle migration time. The weight of the release position on particle migration time is 63%, while the impact of valve surface roughness is 37%. In models with different roughness levels, the particle migration time increases more rapidly for roughness values greater than Ra0.4, while for values less than Ra0.4, the increase in migration time is slower. Furthermore, the study reveals that particle migration trajectories are independent of flow velocity, with velocity only affecting particle migration time. This research provides theoretical support for enhancing the reliability of fuel electro-hydraulic servo valves and offers a new perspective for the design of highly reliable hydraulic components. Full article

Hydraulic excavators operate in harsh environments where direct measurement of actuator chamber pressures and boom displacement is often unreliable or infeasible. This study presents a novel control strategy that estimates actuator chamber pressures from work port pressures using differential equations, eliminating the need for direct pressure or position sensors. A fuzzy logic-based proportional–derivative (PD) controller is developed to mitigate boom oscillations, particularly under high-inertia load conditions and variable operator inputs. The controller dynamically adjusts gains through fuzzy logic-based gain scheduling, enhancing adaptability across a wide range of operating conditions. The proposed method addresses the limitations of classical PID controllers, which struggle with the nonlinearities, parameter uncertainties, and instability introduced by counterbalance valves and pressure-compensated proportional valves. Experimental data is used to design fuzzy rules and membership functions, ensuring robust performance. Simulation and full-scale experimental validation demonstrate that the fuzzy PD controller significantly reduces pressure overshoot (by 23% during extension and 32% during retraction) and decreases settling time (by 31.23% and 28%, respectively) compared to conventional systems. Frequency-domain stability analysis confirms exponential stability and improved damping characteristics. The proposed control scheme enhances system reliability and safety, making it ideal for excavators operating in remote or rugged terrains where conventional sensor-based systems may fail. This approach is generalizable and does not require modifications to the existing hydraulic circuit, offering a practical and scalable solution for modern hydraulic machinery. Full article

Asset Management (AM) is quickly transforming due to the digital revolution induced by Industry 4.0, in which Cyber–Physical Systems (CPS) and Digital Twins (DT) are taking key positions in monitoring and optimizing physical assets. With more intelligent functionalities arising in industrial contexts, Machine Learning (ML) has transitioned from playing a supporting role to becoming a core constituent of asset operation. However, while the Asset Administration Shell (AAS) has become an industry standard format for digital asset representation, incorporating ML models into this format is a significant challenge. In this research, a control valve, a common asset in industrial equipment, is used to explore the modeling of a machine learning model as an AAS submodel, including its related elements, such as parameters, hyperparameters, and metadata, in accordance with the latest guidelines issued by the Industrial Digital Twin Association (IDTA) in early 2025. The main contribution of this work is to clarify basic machine learning principles while demonstrating their alignment with the AAS framework, hence facilitating the further development of smart and interoperable DTs in modern industrial environments. Full article

Solar-powered pumping systems using series pumps are commonly applied in the delivery of water to remote agricultural regions, particularly in hilly tropical terrain. The synchronization of these pumps typically depends on reliable communication; however, dense vegetation, elevation changes, and weather conditions often disrupt signals. To address these limitations, a fully decentralized, communication-free control system is proposed. Each pumping station operates independently while maintaining synchronized operation through emulated neighbor sensing. The system applies a discrete-time control algorithm with virtual sensing that estimates neighboring pump statuses. Each station consists of a solar photovoltaic (PV) array, variable-speed drive, variable inlet valve, reserve tank, and local control unit. The controller adjusts the valve positions and pump power based on real-time water level measurements and virtual neighbor sensing. The simulation results across four scenarios, including clear sky, cloudy conditions, temporary outage, and varied irradiance, demonstrated steady-state operation with no water overflow or shortage and a steady-state error less than 4% for 3 m³ transfer. The error decreased as the average power increased. The proposed method maintained system functionality under simulated power outage and variable irradiance, confirming its suitability for remote agricultural areas where communication infrastructure is limited. Full article

To advance the construction of intelligent mining, electro-hydraulic digital control technology has emerged as a critical direction for the digital transformation of mining machinery. This study proposes a digital control scheme based on the pressure state of the system and the operating state of the actuator. The scheme utilises a novel convergence rate sliding film position control method to regulate the system pressure in real time by controlling the pilot valve, which is driven by a permanent magnet synchronous motor (PMSM). Moreover, a prototype of an incremental digital pressure control valve was developed for high-pressure, high water-based working conditions. A simulation model of the valve was established using AMESim/Simulink, and dynamic characteristics under various operating conditions were analyzed. The relative error between simulated and experimental pressure results remained within ±4.7%. Finally, a multi-parameter optimization was conducted using a genetic algorithm. The results demonstrate that the optimized digital pressure control valve achieved a stabilized inlet pressure within 44.8 ms, with a pressure overshoot of 4.1% and a response time of 20.1 ms, exhibiting excellent real-time dynamic pressure regulation capabilities. This study provides a theoretical foundation and practical reference for comprehensive research on pressure control in underground emulsion pump stations. Full article