Color constancy with an optimized regularized random vector functional link based on an improved equilibrium optimizer.

In order to improve the accuracy of illumination estimation, this paper proposes a color constancy algorithm based on an improved equilibrium optimizer (IEO) to optimize the network structure parameters and common parameters of the regularized random vector functional link (RRVFL) at the same time. First, the initial search agent (population) of the equilibrium optimizer algorithm is generated through opposition-based learning, and the particles (individuals in the population) of the search agent are updated using the IEO algorithm. Compared with the completely randomly generated search agent, the method of initializing the search agent through the IEO algorithm has a better convergence effect. Then, each segment of the search agent is mapped to the corresponding parameters of the RRVFL, and the effective input weight and hidden layer bias are selected according to the node activation to generate the network structure, which can realize the simultaneous optimization of hyperparameters and common parameters. Finally, by calculating the output weight, the light source color prediction of the image under unknown illumination is performed, and the image is corrected. Comparison experiments show that the IEO-RRVFL color constancy algorithm proposed in this paper has higher accuracy and better stability than other comparison algorithms.

Effects of different thermal insulation methods on the nasopharyngeal temperature in patients undergoing laparoscopic hysterectomy: a prospective randomized controlled trial.

BACKGROUND: This study explored the comparison of the thermal insulation effect of incubator to infusion thermometer in laparoscopic hysterectomy. METHODS: We assigned 75 patients enrolled in the study randomly to three groups: Group A: Used warming blanket; group B: Used warming blanket and infusion thermometer; group C: Used warming blanket and incubator. The nasopharyngeal temperature at different time points during the operation served as the primary outcome. RESULTS: The nasopharyngeal temperature of the infusion heating group was significantly higher than that of the incubator group 60 min from the beginning of surgery (T3): 36.10 ± 0.20 vs 35.81 ± 0.20 (P<0.001)90 min from the beginning of surgery (T4): 36.35 ± 0.20 vs 35.85 ± 0.17 (P<0.001). Besides, the nasopharyngeal temperature of the incubator group was significantly higher compared to that of the control group 60 min from the beginning of surgery (T3): 35.81 ± 0.20 vs 35.62 ± 0.18 (P<0.001); 90 min from the beginning of surgery (T4): 35.85 ± 0.17 vs 35.60 ± 0.17 (P<0.001). Regarding the wake-up time, that of the control group was significantly higher compared to the infusion heating group: 24 ± 4 vs 21 ± 4 (P = 0.004) and the incubator group: 24 ± 4 vs 22 ± 4 (P = 0.035). CONCLUSION: Warming blanket (38 °C) combined infusion thermometer (37 °C) provides better perioperative thermal insulation. Hospitals without an infusion thermometer can opt for an incubator as a substitute. TRIAL REGISTRATION: This trial was registered with ChiCTR2000039162 , 20 October 2020.

Preference Parameters for the Calculation of Thermal Conductivity by Multiparticle Collision Dynamics.

Calculation of the thermal conductivity of nanofluids by molecular dynamics (MD) is very common. Regrettably, general MD can only be employed to simulate small systems due to the huge computation workload. Instead, the computation workload can be considerably reduced due to the coarse-grained fluid when multiparticle collision dynamics (MPCD) is employed. Hence, such a method can be utilized to simulate a larger system. However, the selection of relevant parameters of MPCD noticeably influences the calculation results. To this end, parameterization investigations for various bin sizes, number densities, time-steps, rotation angles and temperatures are carried out, and the influence of these parameters on the calculation of thermal conductivity are analyzed. Finally, the calculations of thermal conductivity for liquid argon, water and Cu-water nanofluid are performed, and the errors compared to the theoretical values are 3.4%, 1.5% and 1.2%, respectively. This proves that the method proposed in the present work for calculating the thermal conductivity of nanofluids is applicable.

Influence of Nanoparticles on the Evaporation Behavior of Nanofluid Droplets: A Dh Law and Underlying Mechanism.

The evaporation behaviors of droplet containing nanoparticles play an important role in nanofluid combustion, spray drying, and so on. The average evaporation rate of a nanofluid droplet will decrease sharply at the end stage of droplet evaporation because the aggregation of nanoparticles on the surface of the droplet results in a shell. To illustrate the microscopic mechanism for the variation of the average evaporation rate and surface tension caused by the copper nanoparticles on the surface of the water droplet, numerical simulations based on the Brownian dynamics are conducted to study the effects of nanoparticle behaviors on the average evaporation rate and surface tension for various initial volume fractions and various distributions of nanoparticles. The results show us that the nanoparticles' distribution and the initial volume fraction of nanoparticles will greatly affect the average evaporation rate of the nanofluid droplet. Therefore, a Dh law can be expected due to the effects of added copper nanoparticles on the evaporation behavior where h will vary with the initial volume fraction and distribution of nanoparticles. Comparisons to the published results indicate that the exponent h = 2.0 for pure liquid, h < 2.0 when lyophilic nanoparticles are added, and h > 2.0 when lyophobic nanoparticles are added. In general, the most important factors to affect the evaporation rate are the volume fraction, distribution, and lyophilic nature of nanoparticles.

Analysis and Optimization of Trapezoidal Grooved Microchannel Heat Sink Using Nanofluids in a Micro Solar Cell.

It is necessary to control the temperature of solar cells for enhancing efficiency with increasing concentrations of multiple photovoltaic systems. A heterogeneous two-phase model was established after considering the interacting between temperature, viscosity, the flow of nanofluid, and the motion of nanoparticles in the nanofluid, in order to study the microchannel heat sink (MCHS) using Al2O3-water nanofluid as coolant in the photovoltaic system. Numerical simulations were carried out to investigate the thermal performance of MCHS with a series of trapezoidal grooves. The numerical results showed us that, (1) better thermal performance of MCSH using nanofluid can be achieved from a heterogeneous two-phase model than that from single-phase model; (2) The effects of flow field, volume fraction, nanoparticle size on the heat transfer enhancement in MCHS were interpreted by a non-dimensional parameter NBT (i.e., ratio of Brownian diffusion and thermophoretic diffusion). In addition, the geometrical parameters of MCHS and the physical parameters of the nanofluid were optimized. This can provide a sound foundation for the design of MCHS.

The impact of pre-compression and temperature on perfluoroalkoxy alkane springs: Insights into spring relaxation.

A predictive model was proposed for determining the high-temperature free height of perfluoroalkoxy alkane springs in air-operated double-bellow pumps with the aim of investigating their relaxation. The model incorporates classical spring deformation theory and considers the material, structure, and real-world operating conditions of the perfluoroalkoxy alkane springs. Experimental validation of the model is also conducted. This study examines the effects of varying temperatures and pre-compression values on the relaxation of perfluoroalkoxy alkane springs' free height. It collects relaxation curves under different temperatures and various pre-compression conditions. The results indicate that spring relaxation increases with higher temperatures when there is no pre-compression. Furthermore, increasing pre-compression at the same temperatures leads to greater spring relaxation. Pre-compression has a more significant impact on spring relaxation. By comparing the experimental data with the simulated curve generated by the model, it is evident that the predicted spring free height relaxation closely aligns with the actual measurements. This verification demonstrates the effectiveness and accuracy of the proposed model in evaluating the relaxation of perfluoroalkoxy alkane springs' free height. Moreover, the model provides a valuable tool for predicting the lifespan of similar perfluoroalkoxy alkane springs in engineering applications.

Robot manipulator visual servoing based on image moments and improved firefly optimization algorithm-based extreme learning machine.

We propose an improved extreme learning machine (ELM) to solve the decoupling problem between the camera coordinates and the image moment features for robot manipulator image-based visual servoing system, that is, determine the nonlinear relationship between them. First, an improved firefly optimization algorithm (IFOA) based on an adaptive inertial weight and individual variations is proposed. Then, the IFOA is optimized the weight and hidden bias in ELM algorithm; this improves the training accuracy of the ELM. Finally, the improved firefly optimization algorithm is integrated into ELM (IFOA-ELM) to solve the decoupling problem and ensure stable performance. The results of experiment show that the estimated error of the rotation angle around the camera frame in the visual servoing system determined by the IFOA-ELM algorithm is less than 0.25°, confirming that the proposed algorithm exhibits good robustness and stability.

Assessment of Turning Polytetrafluoroethylene External Cylindrical Groove with Curvilinear Profile Tool.

Polytetrafluoroethylene (PTFE) is extensively used in equipment used for manufacturing semiconductor components and wet etching equipment. However, achieving ideal dimensional accuracy when cutting PTFE is challenging. In this study, we performed cutting experiments using a curvilinear tool and analyzed cutting force, cutting temperature, groove width, and surface roughness in PTFE grooving. The results indicated that the cutting force was most notably affected by the feed rate in Stage I of grooving. The rate of change in cutting force was the largest in Stage II because of the increase in the tool contact area. In Stage III, the shear area of the rake face was the largest, and the cutting force tended to be stable. The groove width was measured with a minimum error rate of 0.95% at a feed rate of 0.05 mm/rev. Moreover, the groove exhibited a time-independent springback. The minimum groove surface roughness was 0.586 at a feed rate of 0.05 mm/rev. The ideal feed rate was 0.05 mm/rev with groove width, surface quality, and chip curl as the key parameters. The processing parameters obtained in this study can be applied to actual production for the optimization of manufacturing accuracy.

Numerical Investigation on the Heat and Mass Transfer in Microchannel with Discrete Heat Sources Considering the Soret and Dufour Effects.

Heat-transfer enhancement in microchannel heat sinks (MCHS) has been a hot topic in the last decade. However, most published works did not focus on the heat sources that are discrete, as in most microelectronic devices, and the enhancement of heat and mass transfer (HMT) due to the Soret and Dufour effects being ignored. Based on a heterogeneous two-phase model that takes into consideration the Soret and Dufour effects, numerical simulations have been performed for various geometries and heat sources. The numerical results demonstrate that the vortices induced by a heat source(s) can enhance the heat transfer efficiency up to 2665 W/m2·K from 2618 W/m2·K for a discrete heat source with a heat flux q = 106 W/m2. The Soret effect can affect the heat transfer much more than the Duffour effect. The integrated results for heat transfer due to the Soret and Dufour effects are not sampled superpositions. Discrete heat sources (DHS) arranged in microchannels can enhance heat transfer, especially when the inlet velocity of the forced flow is less than 0.01 m/s. This can provide a beneficial reference for the design of MCHS with DHS.

Passive tracking of underwater acoustic targets based on multi-beam LOFAR and deep learning.

Conventional passive tracking methods for underwater acoustic targets in sonar engineering generate time azimuth histogram and use it as a basis for target azimuth and tracking. Passive underwater acoustic targets only have azimuth information on the time azimuth histogram, which is easy to be lost and disturbed by ocean noise. To improve the accuracy of passive tracking, we propose to adopt the processed multi-beam Low Frequency Analysis and Recording (LOFAR) as the dataset for passive tracking. In this paper, an improved LeNet-5 convolutional neural network model (CNN) model is used to identify targets, and a passive tracking method for underwater acoustic targets based on multi-beam LOFAR and deep learning is proposed, combined with Extended Kalman Filter (EKF) to improve the tracking accuracy. The performance of the method under realistic conditions is evaluated through simulation analysis and validation using data obtained from marine experiments.

Neutrally Buoyant Particle Migration in Poiseuille Flow Driven by Pulsatile Velocity.

A neutrally buoyant circular particle migration in two-dimensional (2D) Poiseuille channel flow driven by pulsatile velocity is numerical studied by using immersed boundary-lattice Boltzmann method (IB-LBM). The effects of Reynolds number (25≤Re≤200) and blockage ratio (0.15≤k≤0.40) on particle migration driven by pulsatile and non-pulsatile velocity are all numerically investigated for comparison. The results show that, different from non-pulsatile cases, the particle will migrate back to channel centerline with underdamped oscillation during the time period with zero-velocity in pulsatile cases. The maximum lateral travel distance of the particle in one cycle of periodic motion will increase with increasing Re, while k has little impact. The quasi frequency of such oscillation has almost no business with Re and k. Moreover, Re plays an essential role in the damping ratio. Pulsatile flow field is ubiquitous in aorta and other arteries. This article is conducive to understanding nanoparticle migration in those arteries.

The 95% effective dose of nalbuphine in patient-controlled intravenous analgesia for patients undergoing laparoscopic total hysterectomy compared to equivalent sufentanil.

PURPOSE: To evaluate the 95% effective dose of nalbuphine in patient-controlled intravenous analgesia (PCIA) by the sequential method and compare the analgesia efficacy with the equivalent dose of sufentanil on patients undergoing laparoscopic total hysterectomy. METHODS: In the first part, we defined a successful analgesia as the highest VAS ≤3 in 24 hours postoperatively. On the contrary, a failed analgesia was the highest VAS>3. According to the last patient's outcome, the next patients would be given an increase or decreased dose grade. This process ended up with 9 cross-over points. In the second part, 60 patients undergoing laparoscopic total hysterectomy were selected. They were randomly divided into 2 groups (n = 30 each group): receiving sufentanil 1.78 µg/kg (group S) and nalbuphine 1.78 mg/kg (group N). PCIA pump was given at the end of the operation with 5 mL bonus loading. The total amount of PCIA was 100 mL and programmed to deliver 0.5 mL each time with a lockout interval of 15 minutes and the background infusion amount of 2 mL/h. The VAS score and Ramsay score of were collected after the operation, the number of effective pressing times of PCIA were also recorded. Adverse reactions were documented in detail. RESULTS: The 95% effective dose of nalbuphine in PCIA on patients undergoing laparoscopic total hysterectomy was 1.78 mg/kg. There was no significant difference in VAS between the sufentanil group and the nalbuphine groups (P > .05), but the number of the use of PCIA in the group S was more than that in the group N obviously (P <.05). The group S has a lower ramsay sedation score than group N at every time point. (P <.05). The incidence of nausea and vomiting was not statistically significant differences between two groups in the first 24 hours after colonoscopy (P >  q .05). CONCLUSION: Nalbuphine 1.78 mg/kg in PCIA is recommended for the patients undergoing laparoscopic total hysterectomy. And nalbuphine is a reasonable alternative to sufentanil when used in PCIA.

A Review on Heat Transfer of Nanofluids by Applied Electric Field or Magnetic Field.

Nanofluids are considered to be a next-generation heat transfer medium due to their excellent thermal performance. To investigate the effect of electric fields and magnetic fields on heat transfer of nanofluids, this paper analyzes the mechanism of thermal conductivity enhancement of nanofluids, the chaotic convection and the heat transfer enhancement of nanofluids in the presence of an applied electric field or magnetic field through the method of literature review. The studies we searched showed that applied electric field and magnetic field can significantly affect the heat transfer performance of nanofluids, although there are still many different opinions about the effect and mechanism of heat transfer. In a word, this review is supposed to be useful for the researchers who want to understand the research state of heat transfer of nanofluids.

Investigation on Inertial Sorter Coupled with Magnetophoretic Effect for Nonmagnetic Microparticles.

The sizes of most prokaryotic cells are several microns. It is very difficult to separate cells with similar sizes. A sorter with a contraction-expansion microchannel and applied magnetic field is designed to sort microparticles with diameters of 3, 4 and 5 microns. To evaluate the sorting efficiency of the designed sorter, numerical simulations for calculating the distributions of microparticles with similar sizes were carried out for various magnetic fields, inlet velocities, sheath flow ratios and structural parameters. The numerical results indicate that micro-particles with diameters of 3, 4 and 5 microns can be sorted efficiently in such a sorter within appropriate parameters. Furthermore, it is shown that a bigger particle size and more powerful magnetic field can result in a greater lateral migration of microparticles. The sorting efficiency of microparticles promotes a lower inlet velocity and greater sheath flow ratios. A smaller contraction-expansion ratio can induce a greater space between particle-bands. Finally, the micro particle image velocity (micro-PIV) experiments were conducted to obtain the bandwidths and spaces between particle-bands. The comparisons between the numerical and experimental results show a good agreement and make the validity of the numerical results certain.

RETRACTED: Uncalibrated dynamic visual servoing via multivariate adaptive regression splines and improved incremental extreme learning machine.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the authors and with the Editor-in-Chief's approval due to errors in Figures 9-10 under Section 6. The authors apologise for the inconvenience caused to readers.

Parametric Investigation on a Micro-Array Heat Sink with Staggered Trapezoidal Bumps.

More efficient heat sinks are required due to the rapid increase of power density in microelectronic devices. In this study, a micro-array heat sink with stagger trapezoidal bumps was designed. Numerical simulations for the flow and heat transfer under various conditions were carried out to help us to fully understand the mechanisms of the heat transfer enhancement in such a heat sink. The effects of the structure of the heat sink, parameters of the bumps, and volume fraction of the nanofluid on the performance of heat sink were studied. The results show us that the bumps in the heat sink can result in chaotic convection, interrupting the thermal boundary layer and increasing the cooling area, subsequently improving the heat transfer performance. Furthermore, parametric investigations for trapezoidal bumps were conducted to obtain preferential values for parameters, such as the bump width, fore rake angle of the bump, bump height, and bump pitch.