Performance Characteristics Research Articles

Kinematic characteristics of elastic screen surface and screening performance of material groupsunder different additional excitation conditions

ABSTRACT Screening is indispensable process, which is extensively used in coal separation on a global scale. In traditional screening, material stratification is difficult to achieve, which leads to a poor screening effect. In this study, balls are added under the elastic screen surface to increase the screen amplitude and promote the loose stratification of materials. The screen surface motion characteristics, the changes of the material layer on the screen, the material distribution characteristics under the screen, and the screening efficiency are studied by means of vibration tests, high-speed dynamic recording, and screening tests. The experimental results show that when 2-ball additional excitation is applied, the highest screening efficiency of 79.45% is reached, the elastic screen surface can produce a large amplitude of up to 24.77 mm, the screen surface deformation is larger, the material layer is looser, material migration is faster, and the screening effect is better. The main screening area of the material is the second sections of the screening surface, and the screening efficiency of fine particles is mainly affected by the screening efficiency of complex excitation screening. With the increase of the screening surface length, the screening effect of complex excitation elastic screening becomes better.

Performance characteristics of shell and tube heat exchanger using sectoral baffle

Shell and tube heat exchangers (STHX) play a vital role in a wide range of industrial processes and daily applications. The finite element method was used to solve continuity, momentum, energy, and k-ε turbulent equations that govern STHX. The simulation procedure (SP) was applied to STHX with a single segmental baffle (SB) and 90º, 120º, and 150º sectoral baffles (STB). The baffles were arranged along the tube at 0º, 60º, 120º, 180º, 240º, and 300º orientations. The SP was run at 323.15 and 278.15 K inlet temperatures for shell and tube, respectively, using water as shell-side fluid at a flow rate ranging from 0.5 to 2.50 kg/s. Velocities, temperatures, and pressure obtained from SP were used to evaluate the Relative Performance Index of all the STBs against SB as control. The numerical values of heat transfer coefficient (HTC) and pressure drops (PD) over the shell side along the length of STHX were compared with those obtained from Kern’s method, HTC of STBs was enhanced by 45%, 50%, 55%, 50%, 61%, and 50% with PD of 40%, 25%, 11%, 22%, − 21%, and 22% and performance evaluation coefficient (Q/ΔP) of 63%, 60%, 56%, 59%, 47%, and 59% with field synergy number of 41%, 47%, 53%, 46%, 59%, and 46% for STB90°, RSTB90°, STB120°, RSTB120°, STB150°, and RSTB150° respectively. From the analysis, it was evident that both the 90º and 120º sectoral baffles outperformed the SB, with the 90º sectoral baffle emerging as the most efficient configuration among all those evaluated. This study underscores the importance of baffle design in optimizing heat transfer performance in shell and tube heat exchangers.

Computer simulation approaches to evaluate the interaction between analytical performance characteristics and clinical (mis)classification: a complementary tool for setting indirect outcome-based analytical performance specifications.

Simulation-based approaches for setting indirect outcome-based analytical performance specifications (APS) predominantly involve test repetition through analytical reruns or resampling. These methodologies assess the agreement between original and simulated measurement results, determining the APS corresponding to pre-established performance thresholds. For APS related to imprecision and bias, both analytical performance characteristics (APCs) aretypically considered in simulations, whereas for APS regarding measurement uncertainty, bias is excluded in alignment with traceability standards. This paper introduces the "APS Simulator," a novel tool designed to complement the existing APS Calculator by simulating APS under various scenarios involving imprecision, bias, and measurement uncertainty. The APS Simulator facilitates simulations usingdistinct analytical rerun and resampling models, enabling laboratory professionals to explore a wide range of performance levels for their specific needs. While the APS Simulator provides valuable insights, significant challenges remain in the broader application of indirect outcome-based APS. These include incorporating sources of diagnostic uncertainty, setting appropriate thresholds for performance metrics, validating clinical decision limits, and accounting for population data characteristics. Addressing these limitations will be essential to enhancing the standardization and robustness of APS determination. The source code and desktop application for the APS Simulator are freely available at https://github.com/hikmetc/APS_Simulator, providing a user-friendly platform for researchers and clinicians to further explore these methodologies.

Treatment Performance and Characteristics of Biofilm Carriers in an Aerobic Waterwheel-Driven Rotating Biological Contactor

Rotating biological contactors (RBCs) are widely utilized in aerobic wastewater treatment due to their high stability, efficiency, and ease of maintenance. The choice of disc carrier material for biofilm formation is a critical factor influencing treatment performance. In the context of rural domestic wastewater treatment, the biofilm carriers must balance cost-effectiveness and high efficiency. This study focuses on the aerobic unit of a combined anoxic denitrification–deodorization filter–aerobic RBC system, specifically, the waterwheel-driven aerobic RBC, and evaluates three types of biofilm carrier media: felt, carbon felt, and nonwoven fabric. The study compares their pollutant removal performance and biofilm enrichment characteristics to identify the optimal material. The results indicate that RBCs using nonwoven fabric as the biofilm carrier exhibit superior nitrification efficiency and biocompatibility compared to the other materials, achieving average removal rates of 84.3% for CODCr and 80.5% for ammonia nitrogen. While the addition of nonwoven fabric slightly reduced the driving efficiency of the waterwheel-driven aerobic RBC, it significantly enhanced oxygen transfer efficiency, which explained the enhanced organic degradation and ammonia nitrification. During the biofilm stable phase, the two-stage waterwheel-driven RBC with a nonwoven fabric carrier achieved average CODCr and ammonia nitrogen removal rates of 86.76 ± 0.85% and 92.15 ± 1.49%, respectively. Nonwoven fabric demonstrates significant potential as a biofilm carrier for aerobic rotating biological contactors.

Tailoring Wear Properties of Nodular Cast Iron through Induction Hardening Optimization

Abstract The current study investigated the wear performances of GGG60 nodular cast iron under different loads after induction hardening at different powers and durations. The background of this study is the optimization of induction hardening parameters applied to increase the wear resistance of GGG60 nodular cast iron, which is the raw material of parts subjected to high wear loads such as crankshafts, gear systems and flywheels. With the obtained wear results, the induction parameters were optimized by RSM. Induction hardening was treated at four induction powers and two induction durations. Wear tests were conducted using the ball-on-disc method under dry wear conditions for 60 min. Three different wear loads of 10, 20, and 30 N were used. The samples were analyzed in terms of microstructure, hardness, and wear characterization. Subsequently, a RSM model was constructed using the wear results Untreated specimens have significantly lower performance characteristics than treated ones. The hardness, penetration depth, and wear performance indicated a strong relationship with the increase in both induction power and duration. The optimization model presented that the most critical parameter of volume loss is the wear load. In addition, induction power and wear load were found to be significant in the wear rate. The model's prediction capacity for volume loss is satisfactory. Nevertheless, the model's prediction capacity for the wear rate experienced a slight decrease. Conclusions indicate the model can estimate the induction hardening parameters.

Influence of Biodiesel from Used Cooking Oil and Sunflower Oil on Engine Efficiency and Emission Profiles

This study evaluates the performance and emissions characteristics of a compression ignition engine fueled with biodiesel blends derived from used cooking oil (UO) and sunflower oil (SF) at concentrations of 5%, 10%, 20%, and 50%. Tests were conducted under different load conditions (20%, 50%, and 100%) across engine speeds ranging from 1500 to 3600 rpm, focusing on effective power, torque, brake specific fuel consumption (BSFC), and emissions of NOx, CO, HC, particulate matter (PM), smoke, and CO2. Consistent engine operating conditions were maintained for all fuel blends. The results indicated that increasing the biodiesel concentration led to a decrease in brake power and torque—up to 3.18% reduction for SF50 compared to diesel—due to the lower calorific value of biodiesel. For SF biodiesel, the BSFC increased with higher biodiesel content, while for UO biodiesel the results varied across concentrations. Emissions analysis revealed lower CO and HC at 2500 rpm for all biodiesel blends relative to diesel, while NOx emissions varied depending on fuel type and concentration. In terms of particles, both PM and smoke were measured, and while PM showed different results across blends, smoke was lower for all blends compared to diesel. Our overall analysis shows that biodiesel blends up to 20% can be effectively used in diesel engines without substantial modifications, offering a balance between performance and reduced emissions.

Photoresponse Design in Metal Oxide Semiconductor TFTs toward Diverse Applications: Display Drivers, Photodetectors, and Optoelectronic Synapses.

Different application domains impose diverse and often conflicting requirements on the optoelectronic performance of metal oxide semiconductor (MOS) thin-film transistors (TFTs). These varying demands present substantial challenges in the selection of TFT materials and the optimization of device performance. This study begins by examining three primary application areas for TFTs: display drivers, photodetectors, and optoelectronic synapses. A comparative analysis of the optoelectronic properties is conducted among various MOS TFTs fabricated by magnetron sputtering, including indium-gallium-zinc-oxide (IGZO, In/Ga/Zn = 1:2:1), indium-gallium-oxide (IGO, In/Ga = 1:1), indium-zinc-oxide (IZO, In/Zn = 1:1), indium oxide (In2O3), and zinc oxide (ZnO). The investigation reveals the significant impact of material selection on key performance metrics essential for these applications, such as photoresponse, the decay rate of photocurrent (Iph), and negative bias illumination stress (NBIS). Additionally, a comprehensive summary of the applicable domains for each type of TFT is provided. The study also explores the correlation between activation energy (Ea) and TFT performance, indicating that higher Ea is associated with a stronger persistent photoconductivity (PPC) effect but poorer stability. Furthermore, the content of oxygen vacancy (VO) shows a positive correlation with the decay rate of Iph. Lastly, the photogenerated carrier lifetime (τ) is derived and compared among the five MOS materials, revealing the potential applications and performance characteristics of each in optoelectronic devices. The findings offer a nuanced understanding of the intrinsic relationships between material properties, defect states, and photoelectric performance, thereby guiding the selection and optimization of channel layer materials for specific application requirements.

Research of tribological properties of surface MAO composites on D16T alloy

Operation of mechanical engineering products operating under conditions of intensive wear at high rotation speeds and loads leads to their inevitable wear and significant metal losses. One of the methods for obtaining wear-resistant surfaces on products, for example, friction pair parts, is the microarc oxidation (MAO) method of aluminum alloys. The method allows obtaining dense hard surface wear-resistant composites based on α-Al2O3 (corundum) and γ-Al2O3. The structure, composition and surface quality of the resulting MAO coating significantly affect the performance characteristics of the product surface. The aim of the work is to determine the effect of porosity (10 and 16%) and surface roughness (Ra, equal to 2.7 and 0.51 μm) of MAO composites on D16T alloy on tribological properties and to evaluate the possibility of using MAO coatings in friction pairs, including end seals, under dry friction conditions. Comparative tests were carried out on an SMT-1 machine under dry friction conditions at a specific pressure in the friction pair of P = 0.5 MPa; the duration of the experiment was 90 – 91 min for each friction pair. The studies have shown that in many friction pairs, various types of damage (destruction) of the coating integrity, as well as deep abrasive wear, occurred. The porosity of the MAO coating in the range of 10 – 16% at different roughness values does not affect the abrasive wear of the coating. However, a porosity of 10% and a surface roughness of no more than Ra ≤ 0.51 ± 0.12 μm are preferable for achieving better tribological characteristics of surface MAO composites on D16T aluminum alloy.

Automatic Generation of Fast and Accurate Performance Models for Deep Neural Network Accelerators

Implementing Deep Neural Networks (DNNs) on resource-constrained edge devices is a challenging task that requires tailored hardware accelerator architectures and a clear understanding of their performance characteristics when executing the intended AI workload. To facilitate this, we present an automated generation approach for fast performance models to accurately estimate the latency of a DNN mapped onto systematically modeled and concisely described accelerator architectures. Using our accelerator architecture description method, we modeled representative DNN accelerators such as Gemmini, UltraTrail, Plasticine-derived, and a parameterizable systolic array. Together with DNN mappings for those modeled architectures, we perform a combined DNN/hardware dependency graph analysis, which enables us, in the best case, to evaluate only 154 loop kernel iterations to estimate the performance for 4.19 billion instructions achieving a significant speedup. We outperform regression and analytical models in terms of mean absolute percentage error (MAPE) compared to simulation results, while being several magnitudes faster than an RTL simulation.

3D Printed Metamaterial Absorber Based on Vanadium Dioxide Phase Transition Control Prepared at Room Temperature

AbstractThe thermal phase transition characteristics of vanadium dioxide can effectively regulate the absorption performance of metamaterial absorbers. A petal‐shaped metamaterial absorber is designed based on vanadium dioxide phase transition control and prepared metamaterial samples using surface projection micro stereolithography (PµSL) 3D printing technology. Then, vanadium dioxide thin films are coated on the surface of the metamaterial using the ultrasonic spraying method. The PµSL 3D printing technology makes it possible to prepare high‐precision complex samples, and the ultrasonic spraying method enables the coating of vanadium dioxide thin films at room temperature. To demonstrate the stability of this method, two different metamaterial structures are prepared: planar structure and hemispherical structure. In the experiment, a non‐contact heating method is used to regulate the temperature of the vanadium dioxide thin film, which made the temperature of the metamaterial sample controllable, stable, and uniformly heated. The experimental results show that the designed metamaterial absorber has excellent modulation performance and excellent switching characteristics, which proves the reliability of the method.

An estimation method for the fuel burn and other performance characteristics of civil transport aircraft; part 3 full flight profile when the trajectory is specified

Abstract If an aircraft’s initial mass, the variation of true airspeed, true rate of climb, wind speed and wind direction with time and the relationship between barometric altitude and local temperature are known, the performance along the entire flight path can be determined. Previously published work has provided the building blocks for a simple, fast, open-source and transparent method to estimate the instantaneous fuel flow rate and the engine overall efficiency, plus several other performance characteristics for turbofan powered, civil transport aircraft. The flight phases of primary interest are the climb, cruise, descent and holding, when the flaps and undercarriage are fully retracted and the engine is providing significant, positive thrust. However, for completeness, an approximate relation is provided for the engine’s ‘flight idle’ condition, together with simple estimates for fuel use during take-off and landing, plus a factor to allow for in-service deterioration. Detailed consideration is also given to the operating limits and relations are developed for the estimation of their location in Mach number and flight level space. To apply the method, a series of characteristic coefficients and constants must be known. Estimates for these quantities have been progressively improved and extended over time. Initially, results were published for 53 aircraft types and variants. The data base has now been extended to 67 entries and this is given in tabular form. Finally, to demonstrate the method’s accuracy, estimates of fuel flow rate are compared with flight data recorder values for 20 complete flights of six different aircraft types.

Nanotweezers for Manipulating Untethered Micro/Nanoscale Bio‐Tools: Principles, Performance, and Highlighted Applications

The rapid advancement of nanotweezers for wireless manipulation of artificial micro‐ and nanoparticles has unlocked unprecedented possibilities in biomedicine. This review delves into optical, electric, and magnetic tweezers, emphasizing their roles in controlling single particles with micro/nanoscale features as miniaturized tools. Instead of providing a comprehensive review, this work highlights a select number of representative historical and contemporary examples of each type of tweezer, covering their rudimental working mechanisms, experimental setups, performance characteristics, and niche biomedical applications. Particularly, the focus lies in providing a quantitative comparison of the performances in spatial precision and degrees of freedom in controlling single particles, along with associated challenges and prospects.

Pericoronary adipose tissue feature analysis in computed tomography calcium score images in comparison to coronary computed tomography angiography.

We investigated the feasibility and advantages of using non-contrast CT calcium score (CTCS) images to assess pericoronary adipose tissue (PCAT) and its association with major adverse cardiovascular events (MACE). PCAT features from coronary computed tomography angiography (CCTA) have been shown to be associated with cardiovascular risk but are potentially confounded by iodine. If PCAT in CTCS images can be similarly analyzed, it would avoid this issue and enable its inclusion in formal risk assessment from readily available, low-cost CTCS images. To identify coronaries in CTCS images that have subtle visual evidence of vessels, we registered CTCS with paired CCTA images having coronary labels. We developed an "axial-disk" method giving regions for analyzing PCAT features in three main coronary arteries. We analyzed hand-crafted and radiomic features using univariate and multivariate logistic regression prediction of MACE and compared results against those from CCTA. Registration accuracy was sufficient to enable the identification of PCAT regions in CTCS images. Motion or beam hardening artifacts were often prevalent in "high-contrast" CCTA but not CTCS. Mean HU and volume were increased in both CTCS and CCTA for the MACE group. There were significant positive correlations between some CTCS and CCTA features, suggesting that similar characteristics were obtained. Using hand-crafted/radiomics from CTCS and CCTA, AUCs were 0.83/0.79 and 0.83/0.77, respectively, whereas Agatston gave AUC = 0.73. Preliminarily, PCAT features can be assessed from three main coronary arteries in non-contrast CTCS images with performance characteristics that are at the very least comparable to CCTA.

Impact of monensin, virginiamycin, trace minerals, and yeast combination on animal performance, carcass and meat characteristics of finishing feedlot bulls fed high grain diet.

This study was realized to evaluate the influence of monensin, virginiamycin,trace minerals and yeast combination on animal performance, feed efficiency, in situ digestibility, feeding behavior, and carcass and meat characteristics from bulls finished in feedlot fed high-grain diet. A total of 36 (European vs. Nellore) bulls at 24 ± 3.2months of age and with a body weight (BW) of 385.5 ± 3.84kg were used in a completely randomized design. The four experimental diets were: CONT - without additives; MONE - inclusion of 30mg of monensin/kg of DM; MOVI - inclusion of 30mg of monensin + 30mg of virginiamycin/kg of DM; MOMY - inclusion of 30mg of monensin/kg of DM + 0.3g/kg of BW of trace minerals and yeast. Final body weight was higher (P < 0.05) for the bulls fed MOVI (558.7kg) and MOMY (554.6kg) diets, intermediate for bulls fed MONE (529.3kg) diet, and lower for bulls fed CONT (514.6kg) diet. Likewise, the average daily gain was higher (P < 0.01) for bulls fed MOVI and MOMY (2.02kg/d), intermediate for bulls fed MONE (1.72kg/d), diet and lower for bulls fed CONT (1.57kg/d) diets. Dry matter intake and other nutrients were similar (P > 0.05) among treatments. However, feed conversion improved (P < 0.05) for bulls fed MOVI and MOMY diets. Animals fed MOVI and MOMY spent more time ruminating compared to animals fed CONT and MONE (P = 0.034) diets. The carcass weights, carcass dressing and backfat thickness were greater (P < 0.05) for the bulls fed MOVI and MOMY diets. In conclusion, the inclusion of monensin or a combination of monensin + virginiamycin or monensin + trace minerals and yeast resulted in higher animal performance and improved feed efficiency.

External validation of a CT score for predicting ischaemia in adhesive small-bowel obstruction.

To assess the diagnostic accuracy, in a validation cohort, of a score based on three CT items, which has shown good performance for predicting ischaemia complicating acute adhesive small-bowel obstruction (SBO). This retrospective single-centre study of diagnostic accuracy included consecutive patients admitted for acute adhesive SBO in 2015-2022, who were treated conservatively or underwent surgery within 24 h after CT. The gold standard for ischaemia was an intraoperative diagnosis for operated patients, while the absence of ischaemia was confirmed either by its absence during surgery or by clinical follow-up in patients who did not undergo surgery. Three radiologists independently assessed the three score items, namely, decreased bowel-wall enhancement, diffuse mesenteric haziness, and closed-loop mechanism. Inter-observer agreement was evaluated by computing Fleiss' kappa. The diagnostic performance characteristics of the score were computed. Of the 164 patients analysed (median age, 70 [57-80] years; 88 [54%] males), 57 (34.8%) had surgery, including 41 (71.9%) with intra-operative evidence of bowel ischaemia, whereas 107 (65.2%) were treated conservatively. A score ≥ 2/3 had a sensitivity of 78% (95% CI: 62-89%), a specificity of 97% (95% CI: 92-99%), a positive predictive value of 89% (95% CI: 74-97%), and a positive likelihood ratio of 24 (95% CI: 9.03-63.79). Adding increased unenhanced bowel-wall attenuation and requiring ≥ 2/4 items did not improve score performance. Fleiss' kappa values indicated moderate to substantial agreement between observers: 0.64 [0.56-0.73] for decreased bowel-wall enhancement, 0.57 [0.48-0.66] for diffuse mesenteric haziness, and 0.68 [0.59-0.76] for closed-loop mechanism. The results of this external validation study support the reproducibility and good diagnostic performance of the score based on three CT items for predicting bowel ischaemia complicating acute adhesive SBO. Question The Millet score with three enhanced CT items for predicting bowel ischaemia complicating acute adhesive SBO has not been assessed in an external validation cohort. Findings Adding "increased unenhanced bowel-wall attenuation" to the "decreased bowel-wall enhancement", "diffuse mesenteric haziness", and "closed-loop mechanism" items did not improve score performance. Clinical relevance In an external validation cohort, a score based on three CT items performed well for predicting ischaemia in patients with acute adhesive SBO and showed acceptable inter-observer agreement. This score may help identify patients for surgery.

Realistic total-body J-PET geometry optimization: Monte Carlo study.

Total-body (TB) Positron Emission Tomography (PET) is one of the most promising medical diagnostics modalities, opening new perspectives for personalized medicine, low-dose imaging, multi-organ dynamic imaging or kinetic modeling. The high sensitivity provided by total-body technology can be advantageous for novel tomography methods like positronium imaging, demanding the registration of triple coincidences. Currently, state-of-the-art PET scanners use inorganic scintillators. However, the high acquisition cost reduces the accessibility of TB PET technology. Several efforts are ongoing to mitigate this problem. Among the alternatives, the Jagiellonian PET (J-PET) technology, based on axially arranged plastic scintillator strips, offers a low-cost alternative solution for TBPET. The work aimed to compare five total-body J-PET geometries with plastic scintillators suitable for multi-organ and positronium tomography as a possible next-generation J-PET scannerdesign. We present comparative studies of performance characteristics of the cost-effective total-body PET scanners using J-PET technology. We investigated in silico five TB scanner geometries, varying the number of rings, scanner radii, and other parameters. Monte Carlo simulations of the anthropomorphic XCAT phantom, the extended 2-m sensitivity line source and positronium sensitivity phantoms were used to assess the performance of the geometries. Two hot spheres were placed in the lungs and in the liver of the XCAT phantom to mimic the pathological changes. We compared the sensitivity profiles and performed quantitative analysis of the reconstructed images by using quality metrics such as contrast recovery coefficient, background variability and root mean squared error. The studies are complemented by the determination of sensitivity for the positronium lifetime tomography and the relative cost analysis of the studiedsetups. The analysis of the reconstructed XCAT images reveals the superiority of the seven-ring scanners over the three-ring setups. However, the three-ring scanners would be approximately 2-3 times cheaper. The peak sensitivity values for two-gamma vary from 20 to 34cps/kBq and are dominated by the differences in geometrical acceptance of the scanners. The sensitivity curves for the positronium tomography have a similar shape to the two-gamma sensitivity profiles. The peak values are lower compared to the two-gamma cases, from about 20-28 times, with a maximum value of 1.66 cps/kBq. This can be contrasted with the 50-cm one-layer J-PET modular scanner used to perform the first in-vivo positronium imaging with a sensitivity of 0.06 cps/kBq. The results show the feasibility of multi-organ imaging of all the systems to be considered for the next generation of TB J-PET designs. Among the scanner parameters, the most important ones are related to the axial field-of-view coverage. The two-gamma sensitivity and XCAT image reconstruction analyzes show the advantage of seven-ring scanners. However, the cost of the scintillator materials and SiPMs is more than two times higher for the longer modalities compared to the three-ring solutions. Nevertheless, the relative cost for all the scanners is about 10-4 times lower compared to the cost of the uExplorer. These properties coupled together with J-PET cost-effectiveness and triggerless acquisition mode enabling three-gamma positronium imaging, make the J-PET technology an attractive solution for broad application inclinics.

Comparison Analysis on the Hydraulic Performance and Flow Characteristics on a Reactor Coolant Pump Under Rated Operating Condition Between Lead–Bismuth Eutectic and Water Mediums

Abstract Advanced Generation IV nuclear reactors aim to enhance the sustainability, passive safety, reliability, and economic efficiency of reactor operations. Within that, the reactor coolant pump is a critical component in the reactor's cooling system, due to the unique characteristics of the transported medium, posing challenges for engineering applications. This study focuses on a mixed-flow nuclear reactor coolant pump, indicating that significant differences in hydraulic performance and flow characteristics arise due to the varying flow Reynolds numbers under identical operating conditions for the two mediums. Research employing quantitative analysis of boundary layer friction losses and flow separation-induced flow blockage elucidates the origins of hydraulic performance differences. Subsequent studies focusing on the flow characteristics within the impeller reveal that, while the flow patterns inside the impeller show no fundamental differences, an increase in Reynolds number intensifies flow slippage phenomenon, partially diminishing the impeller's work capability. Analysis in static components indicates that the stronger centrifugal forces lead to increased nonuniformity in flow distribution within the guide vanes and an amplified wake phenomenon within the outlet pipe.

Hydraulic micromotor powered dissector for minimally invasive therapy

To address the challenges of biopsy and intratumoral drug delivery using microdevices, a miniature multifunctional tethered device that has tissue cutting, biopsy and drug delivery capabilities is presented in this paper. The cutting module in the prototype is hydraulically powered and has an outside diameter (OD) of 2 mm at the tip and a cutter attached to 500 µm drive shaft. The hydraulic micromotor prototype was fabricated using micro additive manufacturing. It was tested using a benchtop set-up and had an average speed greater than 100,000 RPM at a water flowrate of 45 mL/min and a speed of about 34,000 RPM at 15 mL/min flowrate. This micromotor design was numerically modeled using 3D-transient simulations in ANSYS CFX to determine its performance characteristics and internal resistance. Preliminary testing was performed using cutting modules with five cutter geometries on agar tissue phantoms of different concentrations and other biological materials. The dissection ability of the cutting module, its ability to deliver particles, and collect biopsy samples were successfully demonstrated. Scaling the 2 mm OD device further, a 1 mm OD micromotor, with a nominal output shaft diameter of 250 µm, was fabricated and operated with air establishing the proof of concept.Graphical

A novel dielectric elastomer with low modulus and fast response

Abstract Dielectric elastomers (DEs) are highly valued in massive fields of actuators and sensors due to their unique advantages of large actuation strain, fast response speed, high energy density and excellent elasticity. The challenge of balancing the elastic modulus, actuation strain and response speed of DE actuators to stably enhance the actuation performance remains a major issue. In this work, a novel DE was prepared by employing polyurethane acrylate (CN9021) as a crosslinker, n-butyl acrylate as a base monomer and 2-ethylhexyl acrylate (2-EHA) as a functional flexible monomer via a UV curing method. The swelling test indicates a reduction of crosslinking density with the increment of 2-EHA concentration in EHA films. As a consequence, the elastic modulus displays a notable decline while the dielectric constant slightly rises, leading to an enhancement of the actuation sensitivity. More specifically, the elastic modulus of our fabricated EHA-1 is only one-third of the commercial VHB-4910. The developed DEs achieve an actuation strain of nearly 150% with low viscoelasticity and mechanical loss resulting in high response speed and broad operating frequency range to the input dynamic voltages. All these actuation performances are superior to VHB-4910. This work provides a promising strategy for developing DEs with balanced performance and superior actuation characteristics.

Study on the mechanics performance and deformation characteristics of polypropylene fiber-reinforced solid waste-based fill material

Study on the mechanics performance and deformation characteristics of polypropylene fiber-reinforced solid waste-based fill material