Flow Rate Conditions Research Articles

Study of cooling experiment and simulation for edible oil storage

This paper proposes a refrigerant cooling method using an inner tube in a storage tank to improve the cooling performance and thermal uniformity during the storing of edible oil. With a prototype of an oil tank in Central Grain Reserve of Zhenjiang, the experimental oil tank was built in a scale of 50:1. Both natural and manual cooling experiments were carried out for the experimental tank. The manual cooling process involved two supplying modes for the refrigerant tube (top and bottom) and four different refrigerant temperatures (10 ℃, 12 ℃, 14 ℃, 16 ℃). The experimental results show that, compared with natural cooling, manual cooling can effectively reduce the temperature difference and thermal stratification between upper and lower layers. The temperature difference is 6.79 ℃, 1.93 ℃, and 3.67 ℃ for the natural cooling, manual top supplying, and manual bottom supplying mode, respectively. Furthermore, for the two manual modes, the cooling efficiency of bottom supplying is 21.4% higher than that of the top supplying, and the average oil temperature drops by 0.8–1 ℃. Based on experimental results, different working conditions (20, 40, and 60 ml/s) were simulated to determine the optimal flow rate for bottom supplying mode. The simulation results indicate that the low flow rate (20 ml/s) corresponds to the best thermal uniformity, and the maximum temperature has no obvious change under different flow rate conditions. Therefore, it is not necessary to increase the flow rate to improve cooling efficiency considering the rising energy consumption.

Characteristics of high-order silane based Si and SiGe epitaxial growth under 600 ℃

Low temperature Si and SiGe epitaxy have been crucial in the semiconductor industry, prompting interest in high-order silanes as Si precursors. In this study, we investigated the growth characteristics of Si and SiGe epitaxial layers using Si2H6, Si3H8, and Si4H10 precursors by ultra-high vacuum chemical vapor deposition at temperatures between 500℃ and 600 ℃. We examined the effects of each precursor on the growth behaviors through varying temperature and flow rate conditions. For these three precursors, activation energies for Si epitaxy were measured to be below surface H desorption energy, and an increase in the order led to a greater adatom density at equivalent flow rates. In SiGe epitaxy, we observed Ge composition variations with temperature at each Ge-to-Si flow ratio depending on the Si precursors. Si2H6 exhibited almost consistent Ge compositions across temperatures, and the activation energy for SiGe epitaxy was decreased to 1.73 eV when the flow ratio was increased to 1. In comparison, Si3H8 and Si4H10 exhibited negligible changes in Ge compositions for the flow ratios below 0.5, with activation energies of 1.88 and 1.62 eV, respectively. Based on our experimental results, we proposed potential reaction pathways for high-order silane precursors.

Experimental investigation on thermal-hydraulic performance of manifold microchannel with pin-fins for ultra-high heat flux cooling

The manifold microchannel (MMC) with pin-fins is fabricated and its thermal-hydraulic performance is experimentally investigated. The MMC with pin-fins is an embedded cooling device made of a manifold wafer and a microchannel wafer, anodically bonded to form a total thickness of 1 mm. A microchannel wafer has the etched micro pin-fins with a porosity of 0.75, fin diameter of ▪, and fin height of ▪. For comparison, MMC with plate-fins is also fabricated, in which the plate-fins have the same porosity, fin thickness, and fin height as the pin-fins. Experiments are performed using single-phase deionized water as the working fluid with flow rates ranging from 50 to 300 ml/min, corresponding to pumping powers ranging from 0.28 to 33 mW, which enables the dissipation of an effective heat flux up to 1.2 kW/cm2. The experimental results demonstrate that employing pin-fins improves the thermal-hydraulic performance of the MMC heat sinks compared to using the plate-fins: an average 40% reduction in the effective thermal resistance (the total thermal resistance subtracting the conduction resistance) at a fixed pumping power condition. This is attributed to the fact that the MMC with pin-fins exhibits 20% higher heat transfer coefficient and 40% greater effective heat transfer area, even with 25% lower pressure drop on average compared to the MMC with plate-fins. At the highest tested flow rate of 300 ml/min, the MMC with pin-fins successfully dissipates the heat flux of about 1.2 kW/cm2 without phase-change heat transfer while maintaining the heater temperature below ▪. This is achieved with only 7 mW of pumping power, corresponding to the COP of 41,300 – a 5.3-fold increase in the COP compared to the MMC with plate-fins under the identical heater temperature and the flow rate conditions. Therefore, this study suggests that the MMC with pin-fins is an energy-efficient cooling device for the thermal management of ultra-high heat flux electronics.

Experimental and numerical analysis of variable cross-section channel liquid cooling plate for server chips thermal management

Utilizing high-performance chips results in increased heat generation, necessitating more effective heat dissipation method. To address challenges in microchannel liquid cooling plates for server chips cooling the study presents the variable cross-section channel liquid cooling plate designs. To investigate the effect of channel structure on the performance of liquid cooling plate, two types of samples, one featuring side wall ribs and bottom cavities (SC) and the other featuring side wall ribs and bottom waves (SW), are evaluated through experimental analyses under various heating power and flow rate conditions. Comparing their performance to a conventional rectangular channel (RC) liquid cooling plate, their heat transfer and flow attributes were assessed. Finally numerical analysis was conducted to investigate the flow behavior inside the channel and extreme performance prediction were made using the numerical study. Results demonstrate that the SC and SW designs outperform the RC in terms of heat transfer capabilities, despite having the weaker flow characteristics. Under 300 W heat source power, the SW variants enable the heat source surface temperature to stay below 77.8 °C with a 194 mL/min flow rate. Notably, the SW variant showcases lower average heat source surface temperature and demonstrates lower pressure drop compared to the SC variant. As the flow rate increases, the heat transfer efficiency of the SW variant is further amplified while simultaneously highlighting the relatively suboptimal flow behavior of the SC variant. Predictive numerical models underscore that the SW variants offers improved thermal performance when subjected to high heat source power scenarios. Remarkably, under the heat source power of 500 W, a mere augmentation in flow rate proves sufficient to reduce the heat source temperature below the prescribed threshold value. The combination design of side wall ribs and bottom waves should enable a low cost, simple and high efficiency electronics cooling.

Simulation of the Entire Process of an Interbasin Water Transfer Project for Flow Routing

The flow routing process plays a crucial role in underpinning the execution of real-time operations within interbasin water transfer projects (IWTPs). However, the water transfer process within the supplying area is significantly affected by the time lag of water flow over extended distances, which results in a misalignment with the water demand process in the receiving area. Hence, there is an imperative need to investigate the flow routing patterns in long-distance water transfer processes. While MIKE11(2014 version) software and the Muskingum method are proficient in simulating flow routing within a water transfer network, they fall short in addressing issues arising from mixed free-surface-pressure flows in water transfer pipelines. This study enhanced the capabilities of the MIKE11(2014 version) software and the Muskingum method by introducing the Preissmann virtual narrow gap method to tackle the challenge of simulating mixed free-surface-pressure flows, a task unattainable by the model independently. This approach provides a clear elucidation of hydraulic characteristics within the water transfer network, encompassing flow rates and routing times. Furthermore, this is integrated with the Muskingum inverse method to compute the actual water demand process within the supplying area. This methodology is implemented in the context of the Han River to Wei River Diversion Project (HTWDP). The research findings reveal that the routing time for the Qinling water conveyance tunnel, under maximum design flow rate conditions, is 12.78 h, while for the south and north main lines, it stands at 15.85 and 20.15 h, respectively. These results underscore the significance of the time lag effect in long-distance water conveyance. It is noteworthy that the average errors between simulated and calculated values for the south and north main lines in the flow routing process are 0.45 m3/s and 0.51 m3/s, respectively. Compared to not using the Preissmann virtual narrow gap method, these errors are reduced by 59.82% and 70.35%, indicating a significant decrease in the discrepancy between simulated and calculated values through the adoption of the Preissmann virtual narrow gap method. This substantially improves the model’s fitting accuracy. Furthermore, the KGE indices for the flow routing model are all above 0.5, and the overall trend of the reverse flow routing process closely aligns with the simulated process. The relative errors for most time periods are constrained within a 5% range, demonstrating the reasonability and precision of the model.

Numerical investigation of the effect of blade tip loading distribution on tip leakage vortex characteristics in a waterjet pump

The blade tip leakage vortex (TLV) is a common concern for waterjet pump. The TLV are closely related to the load distribution at the blade tip. This paper aims at to investigate the relationship between blade tip load distribution and TLV trajectory and size. The characteristics of tip leakage vortex in a mixed flow pump is investigated by numerical method. The SST k-ω turbulence model is used to predict TLV trajectories. The result shows a good agreement with the visualization results based on high-speed photography (HSP), which validated that the accuracy of numerical method. The numerical results show that the starting point of the TLV, as well as the angle between blade chord and TLV changes with flow rate condition, which related with the blade tip loading. Therefore, the distribution of the load at the top of the leaf necessarily influences the trajectory of the leakage vortex. Comparing the three different loading patterns at the blade tip, it can be seen that as the load moves backwards, the starting position of the leakage vortex at the blade tip moves backwards and the relative angle between the TLV and blade increases.

Investigation of radial force in a high-speed miniature pump

A high-speed miniature pump design is put forth for utilization in the aerospace sector, where the pump’s reliability holds critical importance under microgravity operational conditions. This study focuses on a dynamic bearing-equipped miniature centrifugal pump, chosen for its suitability in investigating radial forces. The prototype of the miniature pump is manufactured and tested by experiments at the rotational speed of 10,000r/min. A good agreement is observed between the numerical predictions and the experimental results. The radial force acting on different blade part has been analyzed for several flow rate conditions using the steady state CFD calculation. It has been found that the radial force exerted on the blade trailing edge exit is the main cause of the total radial force for the impeller. Moreover, using the unsteady CFD simulation, the evolution process of the radial force changing for both the direction and the magnitude with respect to the annular position due to the shaft rotation is discussed in details. The pressure pulsation is also monitored in impeller and volute casing. The results show that the amplitude of the unsteady radial force has a strong relationship with the time it takes for the blade trailing edge exit passing the volute tongue region, while the direction of the radial force hardly changes. The findings of this study contribute to facilitating the broader implementation of the high-speed miniature pump across diverse sectors of society.

Integration of HEC-RAS and HEC-HMS with GIS in Flood Modeling and Flood Hazard Mapping

Floods are among the most devastating disasters in terms of socio-economics and casualties. However, these natural disasters can be managed and their effects can be minimized by flood modeling performed before the occurrence of a flood. In this study, flood modeling was developed for the Göksu River Basin, Mersin, Türkiye. Flood hazard and risk maps were prepared by using GIS, HEC-RAS, and HEC-HMS. In hydraulic modeling, Manning’s n values were obtained from 2018 CORINE data, return period flow rates (Q25, Q50, Q100, Q500) were obtained from HEC-HMS, and the application was carried out on a 5 m resolution digital surface model. In the study area, the water depths could reach up to 10 m, and water speeds were approximately 0.7 m/s. Considering these values and the fact that the study area is an urban area, hazard maps were obtained according to the UK Department for Environment, Food and Rural Affairs (DEFRA) method. The results indicated that possible flood flow rates from Q25 to Q500, from 1191.7 m3/s to 1888.3 m3/s, were detected in the study area with HEC-HMS. Flooding also occurred under conditions of the Q25 flow rate (from 4288 km2 to 5767 km2), and the impacted areas were classified as extremely risky by the DEFRA method.

Cavitation diagnosis method of centrifugal pump based on characteristic frequency and kurtosis

Centrifugal pumps are important equipment in industrial production. At present, vibration signals are often used to diagnose cavitation in centrifugal pumps, but the vibration signals are easy to be disturbed and the fault characteristics are unstable to be detected. In this paper, a single stage centrifugal pump is taken as the study object, and the vibration signals of various parts of the centrifugal pump cavitation state are collected under different flow conditions. The short-time Fourier transform and one-third octave analysis are performed on the filtered signals, and the characteristic frequency of cavitation and the energy near the characteristic frequency with the development of cavitation are obtained. Based on vibration signals, the vibration root mean square (rms) and kurtosis values of different cavitation states are obtained. Flow state, kurtosis, and rms are used as input variables in the double-layer backpropagation neural network model to identify and classify the cavitation states of centrifugal pumps. The results show that the trained neural network model can accurately identify and classify the cavitation state of the centrifugal pump under the conditions of low flow rate, rated flow rate, and large flow rate, and the accuracy is more than 99.5%. This study provides a new technique for diagnosing cavitation in centrifugal pumps.

Investigation on unsteady characteristics of flow separation in a supercritical carbon dioxide centrifugal compressor

As one of the core components of supercritical carbon dioxide (S-CO2) closed Brayton cycle, the efficiency of S-CO2 centrifugal compressor plays a crucial role. Affected by the special thermophysical properties of S-CO2 fluid, the flow mechanism of S-CO2 centrifugal compressor is different from the centrifugal compressor of conventional fluid, such as air. Previous studies have found that the flow separation within the flow domain of this kind of compressor is easily to occur downstream the pressure surface. Many steady computational fluid dynamics (CFD) studies have been conducted on the S-CO2 centrifugal compressors, but few studies focused on the unsteady evolution of this flow separation. In this paper, the unsteady CFD simulation is carried out in the flow passage of a S-CO2 centrifugal compressor. The solution domain of CFD simulation includes compressor blades, diffuser and volute. The performance and the unsteady flow behavior of S-CO2 centrifugal compressor is obtained. Under low flow rate conditions, the flow separation on the pressure surface of the blade of S-CO2 centrifugal compressor is more likely to occur, causing the decrease of compressor performance. This flow separation has strong unsteady characteristics, which deteriorates several times during a rotation cycle, meanwhile the vortex shedding happens. At the time steps of vortex shedding, the pressure near the trailing edge of the impeller fluctuates greatly, indicating that this unsteady flow separation brings a large flow loss to the S-CO2 centrifugal compressor.

NOx formation processes in rotating detonation engines

High-fidelity simulations of RDEs with H2-Air-NOx chemistry are employed to study NOx emissions in such devices. Discrete injection of gaseous hydrogen fuel and continuous injection of air oxidizer is used at various mass flow rate conditions in several 3D RDE simulations to understand resulting NOx production behaviors. Simulations are also performed for two different injector configurations, one in which air is injected axially into the detonation chamber [Axial Air Inlet (AAI)] and one in which air is injected radially [Radial Air Inlet (RAI)]. It is seen that the AAI RDE produces much less NOx than the RAI RDE, mainly due to the weaker waves seen in this system as a result of parasitic combustion losses from product gas recirculation. Parasitic combustion does lead to NOx formation in its own right, but the emissions levels from this process are negligible compared to emissions stemming directly from detonation processes. In regards to detonation strength in particular, it is generally seen that detonation strength increases with increasing mass flow rate, in turn increasing peak pressure, peak heat release and NOx emissions levels. Nevertheless, even the highest recorded NOx levels at the combustor exit in this study remain on the same order of magnitude as compared to gas turbine exhaust emissions levels, supporting the claim that significant differences between detonative and deflagrative combustion do not necessarily lead to significant differences in NOx levels. Overall, this study provides greater understanding into the behaviors of NOx formation in RDEs and how these behaviors are affected by changes in operating parameters.

Evaluation of aging of chemical additives under controlled conditions of pressure, flow rate and temperature

Evaluating stability and performance of chemicals after simulating extreme application conditions is very important for operational success. The aim of this work was to develop and validate an experimental methodology to simulate different field conditions of temperature, pressure, and flow. The apparatus allows the chemical to circulate, alternately, at low (−10 to 10 °C) and high (30 to 200 °C) temperatures, at different pressures (14.7 to 4900 psi) and flow rates (1 to 10 mL/min) and is able to detect the particles formation by observing an increase in pressure. To validate the methodology, four chemicals were selected: two scale inhibitors, one asphaltenes stabilizer, and one pour point depressant, which were previously evaluated for their specific applications. They were submitted to the methodology at selected conditions for 15 days, or until the system pressure increased by own. Then, the chemicals had their performance evaluated again. None of the chemicals presented phase separation or clogged the pipe at the conditions used. Nevertheless, both scale inhibitors had their efficiency decreased, indicating that they cannot be used at the concentration previously stablished. The constructed device is capable of reliably evaluating the response of chemicals under conditions similar to those in the oilfield.

Modeling and simulation of the cavitation phenomenon in turbopumps

This paper presents a model for simulating a two-phase flow involving cavitation and condensation, focusing on its application to turbopump flows. The model is derived by extending Kapila's approach, which incorporates thermal and free energy relaxation terms, to compressible multiphase flow equations in a rotating reference frame. The numerical method employed is a finite volume approach based on the Godunov scheme, ensuring pressure equilibrium and total energy conservation through a relaxation step. The model utilizes separate Equations of State (EOS) for the liquid and vapor phases, with the experimental saturation curve, expressed as psat(T), being the only parameter needed for cavitation modeling. To broaden its applicability beyond axial pumps, a specific Riemann solver is developed to couple rotating and non-rotating regions within the flow domain. The thermodynamic phase change process is validated using simple cases, and the model is further utilized to simulate water flows in a turbopump inducer. The characteristic curve of the pump is obtained in the non-cavitating regime for several mass flow rates conditions, and the model is successfully assessed in severe cavitation conditions, demonstrating the performance breakdown caused by vapor pockets. The modeling also provides detailed flow descriptions, including analysis of vapor pockets and their impact on blade pressure loading.

Research on ionization characteristics of atmospheric pressure pulse-modulated microwave He/air plasma jet

The atmospheric pressure pulsed microwave He plasma jet has the advantages of high electron density and abundant active particles, but its shrinking on the discharge electrode morphology limits its application range. In order to modulate a He plasma jet with a longer plume and study its ionization development characteristics, we constructed a dual-channel pulsed microwave coaxial discharge device. He and air were, respectively, injected into the inner and outer gas channels of the resonator to generate a double-layer atmospheric pressure microwave plasma jet with a longer plume. It is observed that the bifurcation of the stratified plasma jet will occur by changing the gas flow. The ionization development of plasma jet was observed by using enhanced charge-coupled device and microwave Rayleigh scattering apparatus measured the space-time evolution of plasma and observed the three times ionization enhancement process of plasma jet development. The spectral lines of the active products associated with Penning ionization were observed by using a fiber optic spectrometer. A fluid model was constructed to simulate and analyze that under the condition of sufficient He flow rate (He flow rate is above 0.6 slm), there will be sufficient and stable He mole fraction (64%) at the stratification of the plasma jet. The experimental and simulation results show that the jet profile of the microwave He plasma is related to the inlet structure of the discharger and He flow rate. Stratified intake structure can produce stratified He plasma jet, and the unique appearance of bifurcation of jet can be produced by changing the flow rate of He. In the bifurcation process of the plasma jet, the product of Penning ionization inhibits the development of the main branch of the plasma jet, and the secondary electron avalanche of the local electric field promotes the formation of the branch of the plasma jet and is accompanied by the enhancement of the second ionization. The ionization mechanism of microwave He plasma is the resonance excitation of local enhanced electric field, the advance of ionizing waves, and the interaction between the spatially distributed active particles.

Improvement in energy performance from the construction of inlet guide vane and diffuser vane geometries in an axial-flow pump

Advanced inlet guide vane (IGV) and diffuser vane (DV) geometries were constructed in an effort to increase the energy performance of an axial-flow pump at the best efficiency point (BEP). DV setting angles were also investigated to increase energy performance at the off-design points. By integrating the advantages of an adjustable IGV, combinations of adjustable IGV and DV geometries were constructed and thoroughly analyzed by way of energy loss. The asymmetrical geometry of the IGV, upgraded through the use of a hydrofoil profile, resulted in higher hydraulic performance compared to that of the reference model. The efficiency and total head at the BEP increased significantly with the implementation of the new DV, by 1.456% and 5.756% over those of the reference model, respectively. Using the new DV reduced the unsteady turbulent flow behind the trailing edge of the DV under all flow rate conditions, resulting in a reduction in vibration and noise. The positive setting angles of the DV increased the energy performance in the high-flow-rate region, whereas the negative DV setting angles produced a good performance in the low-flow-rate region. Combining an adjustable IGV with an adjustable DV model resulted in a significant increase in the total head, with more optimal energy performance provided by the positive IGV setting angles. At the BEP and under high-flow-rate conditions, the low-velocity zone is closely related to high entropy generation. Furthermore, these high-entropy generation regions follow the trajectory of the low-velocity zones. However, the low-velocity zone is not strongly associated with the high-entropy generation region when operating under low-flow-rate conditions.

Characterization and comparative evaluation of polysulfone and polypropylene hollow fiber membranes for blood oxygenators

AbstractBlood oxygenators are used to saturate oxygen levels and remove carbon dioxide from the body during cardiopulmonary bypass. Although the natural lung is hydrophilic, commercially used oxygenator materials are hydrophobic. Surface hydrophobicity weakens blood compatibility, as long‐term contact with the blood environment may lead to different degrees of blood activity. Polysulfone may be considered an alternative hydrophilic material in the design of oxygenators. Therefore, it may be directed toward developing hydrophilic membranes. This study aims to investigate the feasibility of achieving blood gas transfer with a polysulfone‐based microporous hollow fiber membrane and compare it with the commercially available polypropylene membranes. Structural differences in the membrane morphology, surface hydrophilicity, tortuosity, mass transfer rate, and material properties under different operation conditions of temperature and flow rates are reported. The polysulfone membrane has a water contact angle of 81.3°, whereas a commercial polypropylene membrane is 94.5°. The mass transfer resistances (s/m) for the polysulfone and polypropylene membranes are calculated to be 4.8 × 104 and 1.5 × 104 at 25°C, respectively. The module made of polysulfone was placed in the cardiopulmonary bypass circuit in parallel with the commercial oxygenator, and pH, pO2, pCO2 levels, and metabolic activity were measured in blood samples.

Detailed Protocol for Solid-Phase Extraction for Lipidomic Analysis.

Developing robust analytical techniques is a vital phase to facilitate understanding the roles and impacts of various omic profilings in cellular functions. The comprehensive analysis of various biological molecules within a biological system requires a precise sample preparation technique. Solid-Phase Extraction (SPE) has proven to be an indispensable method in lipidomic analysis, providing an uncomplicated and user-friendly technique for extraction and purification of lipid components from complex biological matrices. Of all the factors influencing the reliability and success of SPE, column or adsorbent materials, flow rate, and storage conditions are paramount in terms of their significance. In this chapter, we will discuss in detail the SPE steps for lipidomic analysis in biofluid samples (serum and plasma) and muscle tissues.

INTEGRATION OF THERMAL ENERGY STORAGE MATERIALS IN HEAT PIPE EVACUATED TUBE SOLAR COLLECTOR SYSTEMS FOR ENHANCED SOLAR THERMAL PERFORMANCE

This study investigates integrating thermal energy storage materials (TESM) with a heat pipe evacuated tube solar collector (HP-ETSC) in a water tank. Three TESMs (paraffin wax, RT27, and RT35) were examined numerically using COMSOL software, and experiments were conducted. Different design parameters were discussed, including water tank thickness, TESM tank thickness, TESM types, flow rate, and environmental conditions. The integration of TESM into the HP-ETSC allows the evaluation of various thermal performances, including average water tank temperature, hot water outlet temperature, and duration of hot water availability after sunset. The findings indicate a maximum temperature difference of approximately 37°C at 13:00 on March 19 without TESM. However, with RT35, the temperature difference is around 34.27°C, and with RT27, it is approximately 33.4°C. Additionally, the temperature difference is approximately 2°C higher when TESM is not utilized during the three months at sunset. These results demonstrate improved thermal performance compared to a similar system without TESM. Thermal energy transmission from TESM to water is relatively low, resulting in slightly higher outlet water temperature at night. During cloudy periods, RT27 and RT35 TESM types maintain their melting temperature from 11:00 to 20:00. A water storage tank thickness of 35 mm yields the highest temperature difference with RT27 and RT35 TESM. Increasing TESM thickness allows for more mass and latent heat storage, leading to up to 3.5 hours of heat release. On a mostly sunny day, such as January 9, the HP-ETSC stops heat release around 16:30 without TESM, while the TESM plates prolong the discharge duration by three hours.

Alginate/GelMA microparticles via oil-free interface shearing for untethered magnetic microbots.

Microrobots hold broad application prospects in the field of precision medicine, such as intravenous drug injection, tumor resection, opening blood vessels and imaging during abdominal surgery. However, the rapid and controllable preparation of biocompatible hydrogel microparticles still poses challenges. This study proposes the one-step direct acquisition of biocompatible sodium alginate and gelatin methacrylate (GelMA) hydrogel microparticles using an oil-free aqueous solution, ensuring production with a controllable generation frequency. An adaptive interface shearing platform is established to fabricate alginate/GelMA microparticles using a mixture of the hydrogel, photoinitiator, and Fe3O4 nanoparticles (NPs). By adjusting the static magnetic field intensity (Bs), vibration frequency, and flow rate (Q) of the dispersed phase, the size and morphology of the hydrogel microparticles can be controlled. These hydrogel microparticle robots exhibit magnetic responsiveness, demonstrating precise rotating and rolling movements under the influence of an externally rotating magnetic field (RMF). Moreover, hydrogel microparticle robots with a specific critical frequency (Cf) can be customized by adjusting the Bs and the concentration of Fe3O4 NPs. The directional in situ untethered motion of the hydrogel microparticle robots can be successfully realized and accurately controlled in the climbing over obstacles and in vitro experiments of animals, respectively. This versatile and fully biodegradable microrobot has the potential to precisely control movement to bone tissue and the natural cavity of the human body, as well as drug delivery.

A preliminary analysis of base saturation flow rate during first loss time and saturated time at pretimed signalized intersections

Saturation flow rate is a key parameter essential for assessing signalized intersection capacity. The reference often used for signalized intersection planning in Indonesia is Indonesian Highway Capacity Guidelines (PKJI, 2023). In heterogeneous traffic environments, it has been observed that driver characteristics and behaviors exhibit significant variations. Therefore, this study aimed to investigate the prevailing saturation flow rate conditions at signalized intersections within Banda Aceh City. This exploration unfolded through two distinct scenarios, namely saturated time with and without initial lost time. For data acquisition, the focus was set on four signalized intersections, namely Jambo Tape, Pocut Baren, AMD Batoh, and Lhong Raya. This extraction procedure aimed to uncover insights into vehicle composition, movement patterns, and field saturation flow rate at these signalized intersections. In the aspect of analysis, a simple linear regression approach was adopted to recalibrate saturation flow rate coefficient of signalized intersections. This recalibration took into account vehicle compositions at the observation locations. The culmination of this analysis showed that in the scenario devoid of lost time under prevailing conditions, flow rate yielded S0 = 352 x Le. Meanwhile, for the scenario entailing lost time, the calculation produced was S0 = 294 x Le.