Search Results (1,610)

Bead-foaming technology effectively addresses production cycles, polymerization control, and cellular structure defects in conventional bulk foaming, especially in high-performance PMI foams. In this work, highly expandable PMI beads were synthesized based on the aqueous suspension polymerization of methacrylic acid-methacrylonitrile-tert-butyl methacrylate (MAA-MAN-tBMA) copolymers. The suspension polymerization was stabilized by reducing the solubility of MAA by the salting-out effect and replacing formamide (a common PMI foaming agent) with tBMA. The polymerization process was optimized by varying salting-out agents, dispersants, water-to-oil ratio (WOR), and stirring speed to achieve uniform bead sizes (0.2–0.4 mm) and high bead yields (>70%). The expansion ratio of the beads can be easily tuned by adjusting tBMA content and foaming time and temperature. Beads with 10%tBMA can reach up to 64 times under a free-forming process at 240 °C, which serves as an excellent precursor toward high-performance in-mold foaming PMI. The beads exhibit excellent in-mold foaming capabilities, thermal stability (Td = 392 °C), and mechanical properties. This work provides a technical foundation for the bead-foaming technology of PMI foams, reducing the cost of PMI foam production and providing the possibility to expand the application of PMI foam in civilian use. Full article

This paper focuses on the design and development of a customized 7-axis suspended robotic arm for automated spraying production lines. The design process considers factors such as workspace dimensions, workpiece sizes, and suspension positions. After analyzing degrees of freedom and workspace coordinates, 3D modeling ensures the arm can reach designated positions and orientations. Servo motors and reducers are selected based on load capacity and speed requirements. A suspended body method allows flexible use within the workspace. Kinematics analysis is conducted, followed by trajectory-tracking experiments using the manifold deformation control method. Results from simulation and real experiments show minimal error in tracking, demonstrating the effectiveness of the control method. Finally, the actual coating thickness sprayed by the 7-axis suspended robotic arm at four locations on the motorcycle shell was measured. The results show that the measured values at each location fall within the standard range provided by the manufacturer, demonstrating consistency in spraying across different regions. This consistency highlights the precision and effectiveness of the robotic arm’s control system in achieving uniform coating thickness, even on complex and curved surfaces. Therefore, the robotic arm has been successfully applied in a factory’s automated spraying production line. Full article

Adhesion-based space climbing robots, with their flexibility and multi-functional capabilities, are seen as a promising candidate for in-orbit maintenance. However, challenges such as uncertain adhesion establishment, unexpected detachment, and body motion unsteadiness in microgravity environments persist. To address these issues, this paper proposes a coordinated force–position compliance control method that integrates novel adhesion establishment and rotational detachment strategies, integrated into the gait schedule for a space climbing robot. By monitoring the foot-end reaction forces in real time, the proposed method establishes adhesion without risking damaging the spacecraft exterior, and smooth detachment is achieved by rotating the foot joint instead of direct pulling. These strategies are dedicated to reducing unnecessary control actions and, accordingly, the required adhesion forces in all feet, reducing the possibility of unexpected detachment. Climbing experiments have been conducted in a suspension-based gravity compensation system to examine the merits of the proposed method. The experimental results demonstrate that the proposed rotational detaching method decreases the required pulling force by 65.5% compared to direct pulling, thus greatly reducing the disturbance introduced to the robot body and other supporting legs. When stepping on an obstacle, the compliant control method is shown to reduce unnecessarily aggressive control actions and result in a reduction in relevant normal and shear adhesion forces in the supporting legs by 44.8% and 35.1%, respectively, compared to a PID controller. Full article

Many endophytic fungi are approved as plant growth stimulants, and several commercial biostimulants have already been introduced in agricultural practice. However, there are still many species of fungi whose plant growth-promoting properties have been understudied or not studied at all. We examined the growth-promoting effect in spring barley (Hordeum vulgare) and Italian ryegrass (Lolium multiflorum) induced by three endophytic fungi previously obtained from the roots of Festuca/Lolium grasses. Surface-sterilized seeds were inoculated with a spore suspension of Cadophora fastigiata (isolate BSG003), Paraphoma fimeti (BSG010), Plectosphaerella cucumerina (BSG006), and their spore mixture. Before harvesting, the inoculated plants were grown in a greenhouse, with the barley being in multi-cavity trays for 30 days and ryegrass being placed in an original cylindric element system for 63 days. All three newly tested fungi had a positive effect on the growth of the barley and ryegrass plants, with the most pronounced impact observed in their root size. The fungal inoculations increased the dry shoot biomass between 11% and 26% in Italian ryegrass, but no such impact was observed in barley. The highest root increment was observed in barley. Herein, P. cucumerina and C. fastigiata inoculations were superior to other treatments, showing an increase in root dry weight of 50% compared to 20%, respectively. All fungal inoculations significantly promoted root growth in Italian ryegrass, resulting in a 20–30% increase in dry weight compared to non-inoculated plants. Moreover, a strong stimulatory effect of the fungi-emitted VOCs on the root development was observed in plate-in-plate arrays. In the presence of C. fastigiata and P. cucumerina cultures, the number of roots and root hairs in barley seedlings doubled compared to control plants. Thus, in our study, we demonstrated the potential of the grass root-derived endophytes C. fastigiata, P. fimeti, and P. cucumerina as growth promoters for spring barley and Italian ryegrass. These studies can be extended to other major crops and grasses by evaluating different fungal isolates. Full article

The paper presents a method for modeling and estimating the orientation of a launch cart in the magnetic suspension system of an innovative UAV catapult. The catapult consists of stationary tracks lined with neodymium magnets, generating a trough-shaped magnetic field. The cart levitates above the tracks, supported by four containers housing high-temperature YBCO superconductors cooled with liquid nitrogen. The Meissner effect, characterized by the expulsion of magnetic fields from superconductors, ensures stable hovering of the cart. The main research challenge was to determine the cart’s orientation relative to the tracks, with a focus on the pitch angle, which is critical for collision-free operation and system efficiency. A dedicated measurement stand equipped with Hall sensors and Time-of-Flight (ToF) distance sensors was developed. Hall sensors mounted on the cart’s supports captured magnetic field data at specific points. To model the tracks, the CRISP-DM (Cross Industry Standard Process for Data Mining) methodology was employed—a structured framework consisting of six stages; from problem understanding and data preparation to model evaluation and deployment. This approach guided the analysis of data-driven models and facilitated accurate pitch angle estimation. Evaluation metrics, including mean squared error (MSE), were used to identify and select the optimal models. The final model achieved an MSE of 0.084°, demonstrating its effectiveness for precise orientation control. Full article

This paper introduces a novel adaptive control method for suspension vehicle systems in response to road disturbances. The considered model is based on an active symmetry quarter car (SQC) fractional order suspension system (FOSS). The word symmetry in SQC refers to the symmetry of the suspension system in the front tires or the rear tires of the car. The active suspension controller is generally driven by an external force like a hydraulic or pneumatic actuator. The external force of the actuator is determined using fractional dynamic sliding mode control (FDSMC) to counteract road disturbances and eliminate the chattering caused by sliding mode control (SMC). In FDSMC, a fractional integral acts as a low-pass filter before the system actuator to remove high-frequency chattering, necessitating an additional state for FDSMC implementation assuming all FOSS state variables are available but the parameters are unknown and uncertain. Hence, an adaptive procedure is proposed to estimate these parameters. To enhance closed-loop system performance, an adaptive proportional-integral (PI) procedure is also employed, resulting in the FDSMC-PI approach. A comparison is made between two SQC suspension system models, the fractional order suspension system (FOSS) and the integer order suspension system (IOSS). The IOSS controller is based on dynamic sliding mode control (DSMC) and a PI procedure (DSMC-PI). The results show that FDSMC outperforms DSMC. Full article

This paper presents a method to design an active suspension controller for 8 × 8 armored combat vehicles, which is called corner damping control (CDC). It is assumed that the target vehicle with 8 × 8 drive mechanisms and 8 suspensions has active actuators on each suspension for vertical, roll and pitch motion control on a sprung mass. A state-space model with 22 state variables is derived from the target vehicle. With the state-space model, a linear quadratic (LQ) cost function is defined. The control objective is to reduce the vertical acceleration, pitch and roll angles of a sprung mass for ride comfort, durability and turret stabilization. To avoid full-state feedback of LQR, a static output feedback control (SOF) is selected as a control structure for CDC. The vertical velocity, roll and pitch rates of a sprung mass, and vertical velocities at each corner, are selected as a sensor output. With those sensor outputs and LQ cost function, four LQ SOF controllers are designed. To validate the effectiveness of the LQ SOF controllers, simulation is carried out on a vehicle simulation package. From the simulation results, it is shown that the proposed CDC with LQ SOF controllers with a much smaller number of sensor outputs and controller gains can reduce the vertical acceleration, pitch and roll angles of a sprung mass and, as a result, improve ride comfort, durability and turret stabilization. Full article

Due to the rapid increase in the use of anti-aging cosmetic products, there is a need to develop valid analytical methods to control their quality. The present work deals with the development and validation of a new chromatographic method for the quantitative determination of five lipophilic components (resveratrol, ferulic acid, quercetin, retinol, and α-tocopherol), with anti-aging properties, in a cold cream (w/o). For the HPLC-UV separation of the active ingredients, an HS, Discovery^® Supelco (Supelco Inc., Bellefonte, PA, USA), C₁₈ column (25 cm × 4.6 mm), 5 μm (at 40 °C) was used as a stationary phase while a binary system of A: Acetonitrile with formic acid 0.2% and B: H₂O with formic acid 0.2%, in gradient elution (flow 1.5 mL·min⁻¹), was used as mobile. The analytical method was validated according to ICH guidelines Q2(R2), where linearity (r² ≥ 0.998), selectivity, precision (% recovery 97.1–101.9), and accuracy (%RSD < 2) were evaluated. The processing of the samples for the recovery of the five analytes from the cream was investigated by experimental design methodology and the cross D-optimal technique (% recovery 98.5–102.9, %RSD < 2%, n = 5). Finally, the same analysis was applied to study the transdermal penetration of the active ingredients incorporated in cold cream (over a period of 8 h). Their behavior was compared with the corresponding one in suspension using Franz cells in a vertical arrangement. The new method is considered reliable for the analysis of the anti-aging product. Full article

This paper presents a method to design a suspension controller with a human body model for ride comfort improvement and motion sickness mitigation. Generally, it has been known that the vertical acceleration of a sprung mass should be reduced for ride comfort. On the other hand, recent studies have shown that, combined, the vertical acceleration and pitch rate of a sprung mass are key factors that cause motion sickness. However, those variables have been considered with respect to the center of gravity of a sprung mass. For motion sickness mitigation, the vertical acceleration of a human head should be also considered. In this paper, the vertical accelerations and pitch rates of a sprung mass and a human head are controlled by a suspension controller for ride comfort improvement and motion sickness mitigation. For the controller design, a half-car and human body models are adopted. With those models, several types of static output feedback suspension controller are designed with linear quadratic optimal control methodology. To reduce the pitch rate of the sprung mass and the vertical acceleration of the head, a filtered-X LMS algorithm is adopted as an adaptive feedforward algorithm and combined with the static output feedback controllers. A frequency response analysis and simulation are performed with the designed controllers on vehicle simulation software, CarSim^®. From the simulation results, it is shown that the proposed controllers can effectively reduce the vertical accelerations and the pitch rate of the sprung mass and the human head. Full article

Background: Insulin pumps coupled with continuous glucose monitoring sensors use algorithms to analyze real-time blood glucose levels. This allows for the suspension of insulin administration before hypoglycemic thresholds are reached or for adaptive tuning in hybrid closed-loop systems. This longitudinal retrospective study aims to analyze real-world glycemic outcomes in a pediatric population transitioning to such devices. Methods: We evaluated children with type 1 diabetes mellitus (T1D) admitted to the Pediatric Diabetes Department from a major University Hospital in Bucharest, Romania, who transitioned to hybrid closed-loop or predictive low-glucose suspend system from either non-automated insulin pumps or multiple daily injections. The primary outcome was assessing the change in glycated hemoglobin (HbA1c) after initiating these devices. Secondary outcomes analyzed changes in glucose metrics from the 90 days prior to the baseline and follow-up visit. Results: 51 children were included (58.8% girls), the mean age was 10.3 ± 3.7 years, and the mean follow-up duration was 13.2 ± 4.5 months. The analyzed parameters, such as HbA1c (6.9 ± 0.7% vs. 6.7 ± 0.6%, p = 0.023), time in range (69.3 ± 11.2% vs. 76 ± 9.9%, p < 0.001), time in tight range (47.4 ± 10.9% vs. 53.7 ± 10.7%, p < 0.001), time below range (5.6 ± 2.9% vs. 3.5 ± 1.9%, p < 0.001), time above range (25 ± 11.2% vs. 20.4 ± 9.4%, p = 0.001), and coefficient of variation (37.9 ± 4.8% vs. 35.6 ± 4.6%, p = 0.001), showed significant improvements. Conclusions: The application of these sensor-integrated insulin pumps can significantly enhance metabolic control in pediatric populations, minimizing glycemic variations to mitigate complications and enrich the quality of life. Full article

Demands for increasing the velocity and load carrying capacity of railway vehicles are a challenge to the passive suspension systems used for isolating the lateral vibrations of the carbody of a railway vehicle, especially under a wide range of vibration frequencies. Semiactive suspension systems, especially systems with a magnetorheological damper (MRD), have been investigated as promising alternatives. Many control algorithms have been developed for fine-tuning the damping force generated by MRDs, but they have been ineffective in isolating carbody vibrations at or around the resonance frequencies of the carbody and bogie. This study aims to develop a mixed control algorithm for a new skyhook (SH) control and a new displacement–velocity (DV) control to improve the effectiveness of vibration isolation in resonance frequency regions while producing high performance across the remaining frequencies. The damping coefficient of the new SH controller depends on the vibration velocity of the components of the suspension system and the skyhook damping variable, whereas that of the new DV controller depends on the velocity and displacement of the components of the suspension system and the stiffness variable. The values of the skyhook damping variable and stiffness variable were identified from the vibration velocity of the carbody using the trial and error method. The results of a numerical simulation problem indicated that the proposed control method worked effectively at low frequencies, similar to the conventional SH–DV controller, whereas it significantly improved ride comfort at high frequencies; at the resonance frequency of the bogie (14.6 Hz), in particular, it reduced the vibration velocity and acceleration of the carbody by 50.85% and 45.39%, respectively, compared with the conventional mixed SH–DV controller. The simplicity and high performance of the new mixed SH–DV control algorithm makes it a promising tool to be applied to the semiactive suspension of railway vehicles in real-world applications. Full article

Integrated Multi-Trophic Aquaculture (IMTA) has been demonstrated to be a very useful tool to minimize the waste product production of fish monocultures whilst promoting biomass that can be used for different purposes. The stable isotope analysis (δ¹³C, δ¹⁵N, and C:N ratio) of bioremediating organisms present in an IMTA facility is critical to understanding the nutrient flow between farm food waste and filter-feeding organisms, and hence the bioremediation capability of the IMTA system. Here, we report the isotopic signature of the sediment below the fish cages, the fish artificial food and sixteen different suspension feeding species present in the IMTA system in the Mar Grande of Taranto (Italy). A comparison of the stable isotopes results of the bioremediating organisms with those of the same species collected from a control (Cnt) site, unaffected by the plant discharges, was thus conducted looking for trophic level patterns. This assessment aimed to evaluate the possible influence of aquaculture waste on the diet of the organisms, revealing these findings for the first time. Similar δ¹⁵N values (below 2–3‰ between areas) were found between the IMTA and Cnt sites, while differences in δ¹³C values were found among multiple organisms between the two sites, suggesting a possible different primary source of the organic matter that supports the trophic web. Almost all analyzed species in the IMTA site reported δ¹³C values lower than Cnt site, being more similar to the isotopic signature of the aquaculture finfish food. However, the wide IMTA isotopic range for both δ¹⁵N and δ¹³C suggested a broad spectrum of diets for bioremediating organisms that can actively mitigate the impacts of mariculture by capturing different particles and using various food sources, leading to more sustainable mariculture activities. Full article

Grouting technology is an important method of ground reinforcement and can effectively improve the stability of engineering rock mass. During overburden isolated grouting in coal mines, the influence of unexpected fractures may lead to substantial grout leakage, resulting in ineffective grouting. The existing natural sedimentation sealing method is mainly applicable to small fractures and low grout flow, while the chemical-reagent rapid-sealing method can cause grouting channel blocking, making it less suitable for overburden isolated grouting. This paper proposes a “capsule” sealing method, detailing the preparation of the sealing material and evaluation of its properties through testing. The sealing material, prepared using the air suspension method, was coated with paraffin on a superabsorbent polymer (SAP) material, which has delayed expansion characteristics. Although this material does not expand within the grouting fractures of overburden rock, it expands rapidly upon entering the leakage channel, accumulating within the channel to achieve effective sealing. A simulation experimental system was designed to simulate the sealing of the slurry leakage channel, and the sealing characteristics were experimentally investigated. Under consistent particle size conditions, a higher film cover ratio led to a more pronounced delayed expansion effect and extended the time required for the sealing material to achieve its maximum expansion. When the content of sealing material with particle sizes of 20 mesh, 40 mesh, and 60 mesh, and a film ratio of 20% was 1.0%, the fractures below 4 mm were effectively sealed. When the fracture aperture is 4–6 mm, the sealing material with a covering ratio of 20% or 30% should have a minimum content of 1.5%, while the sealing material with a covering ratio of 50% should have a minimum content of 2.0%. The findings of this study outline an effective prevention and control method for the sealing of abnormal slurry leakage in overburden isolated grouting engineering. Full article

The aim of this study is to research the flow property of granular materials under nonlinear vibration, which directly affects the stability of the unloading system and the motion state of granules. According to the mechanical constitutive relation, the coupled suspension–tire model with nonlinear ordinary differential equations is established and the kinematic equations of granules are derived. Furthermore, the amplitude–frequency responses of the coupled system and force transmissibility are obtained by the incremental harmonic balance method (IHBM) with high-order approximation, and then the flow characteristics of granular materials are investigated based on the approximate analytic solution under nonlinear vibration. The theoretical analysis and numerical simulation show that the coupled suspension–tire system presents a softening nonlinear feature and the peaks are significantly smaller than that of the linear system, which further affects the motion rules of granular materials. As a result, different sliding states and flow paths are observed under the same operating conditions. This research not only shows the unloading mechanism and vibration transmission characteristics between the continuum structure and granular material but also theoretically explains the control mechanism of the coupled continuum–granular system. The research is instructive in improving the unloading efficiency of granules in practical engineering. Full article

Background: Lipid vesicles, especially those utilizing biocompatible materials like chitosan (CHIT), hold significant promise for enhancing the stability and release characteristics of drugs such as indomethacin (IND), effectively overcoming the drawbacks associated with conventional drug formulations. Objectives: This study seeks to develop and characterize novel lipid vesicles composed of phosphatidylcholine and CHIT that encapsulate indomethacin (IND-ves), as well as to evaluate their in vitro hemocompatibility. Methods: The systems encapsulating IND were prepared using a molecular droplet self-assembly technique, involving the dissolution of lipids, cholesterol, and indomethacin in ethanol, followed by sonication and the gradual incorporation of a CHIT solution to form stable vesicular structures. The vesicles were characterized in terms of size, morphology, Zeta potential, and encapsulation efficiency and the profile release of drug was assessd. In vitro hemocompatibility was evaluated by measuring erythrocyte lysis and quantifying hemolysis rates. Results: The IND-ves exhibited an entrapment efficiency of 85%, with vesicles averaging 317.6 nm in size, and a Zeta potential of 24 mV, indicating good stability in suspension. In vitro release kinetics demonstrated an extended release profile of IND from the vesicles over 8 h, contrasting with the immediate release observed from plain drug solutions. The hemocompatibility assessment revealed that IND-ves exhibited minimal hemolysis, comparable to control groups, indicating good compatibility with erythrocytes. Conclusions: IND-ves provide a promising approach for modified indomethacin delivery, enhancing stability and hemocompatibility. These findings suggest their potential for effective NSAID delivery, with further in vivo studies required to explore clinical applications. Full article