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Pressure drop (Δp) and collection efficiency (η) are used to evaluate the separation performance of the cyclone separator. In this study, we conducted comparative study of cyclone models using response surface methodology (RSM), back propagation neural network (BPNN), and group method of data handling (GMDH) networks to develop optimal predictive cyclone models. Also, we conducted multi-objective optimization for maximizing model and minimizing model using genetic algorithm (GA). CFD was performed instead of experimental method to get the estimated values for modeling of Δp and η. The validation results of CFD showed 0.5% and 2% errors for Δp and η, respectively, compared with the experimental data. Second, design of experiment (DOE) analysis for 10 cyclone geometrical parameters was executed to obtain the significant geometrical parameters. Vortex finder diameter Dx, inlet width a, inlet height b and cone height Hco have a significant effect on η and Δp. However, interaction effects between the geometrical parameters have small effects. The cyclone models by RSM, BPNN and GMDH based on 25 CFD training set were developed. The predictive performance results by the cyclone models were compared by 25 CFD test set. The GMDH method achieved the best prediction for Δp ( ${R^2} = 99.7 $, RMSE = 0.102) $R_{\textrm{adjusted}}^2 = 98.99 $, RMSE = 0.0119) than the RSM, BPNN cyclone models. Additionally, uncertainty analysis was performed to estimate the quantitative performance of cyclone models. The results show that the uncertainty width of GMDH models achieved the best prediction ( $\eta $: ±0.0065, Δp: ±0.0188). Finally, GA was applied to optimize the GMDH models simultaneously. GA generated 70 non-dominant solutions. Reproducibility of five optimal points was validated by using CFD. The trade-off optimal point showed improvement by 24.31%, 18% and 8.79% for Δp ${\textrm{d}_{50}} $ and $\eta $, respectively.

This paper deals with the characteristics of the cyclone separator from the Lagrangian perspective to design important dependent variables, develops a neural network model for predicting the separation performance parameter, and compares the predictive performance between the traditional surrogate model and the neural network model. In order to design the important parameters of the cyclone separator based on the particle separation theory, the force acting until the particles are separated was calculated using the Lagrangian-based CFD methodology. As a result, it was proved that the centrifugal force and drag acting on the critical diameter having a separation efficiency of 50% were similar, and the particle separation phenomenon in the cyclone occurred from the critical diameter, and it was set as an important dependent variable. For developing a critical diameter prediction model based on machine learning and multiple regression methods, Unsteady-RANS analyzes according to shape dimensions were performed. The input design variables for predicting the critical diameter were selected as four geometry parameters that affect the turbulent flow inside the cyclone. As a result of comparing the model prediction performances, the ML model showed the 32.5 % of improvement rate of R2 compared to the traditional MLR considering the nonlinear relationship between the cyclone design variable and the critical diameter. The proposed techniques have proven to be fast and practical tools for cyclone design.

In this paper, the characteristics of the cyclone separator was analyzed from the Lagrangian perspective for designing the important dependent variables. The neural network network model was developed for predicting the separation performance parameter. Further, the predictive performances were compared between the traditional surrogate model and the developed neural network model. In order to design the important parameters of the cyclone separator based on the particle separation theory, the force acting until the particles are separated was calculated using the Lagrangian-based computational fluid dynamics (CFD) methodology. As a result, it was proved that the centrifugal force and drag acting on the critical diameter having a separation efficiency of 50% were similar, and the particle separation phenomenon in the cyclone occurred from the critical diameter, and it was set as an important dependent variable. For developing a critical diameter prediction model based on machine learning and multiple regression methods, unsteady-Reynolds averaged Navier-Stokes analyzes according to shape dimensions were performed. The input design variables for predicting the critical diameter were selected as four geometry parameters that affect the turbulent flow inside the cyclone. As a result of comparing the model prediction performances, the machine learning (ML) model, which takes into account the critical diameter and the nonlinear relationship of cyclone design variables, showed a 32.5% improvement in R-square compared to multi linear regression (MLR). The proposed techniques have proven to be fast and practical tools for cyclone design.

Compact thermo-fluidic systems with complex and narrow gap flow passages, such as heat exchangers, are attractive for use in high energy efficiency applications. However, the narrow gap flow passage limits the experimental evaluations as a result of the size of the commercial sensors and the numerical evaluations of the full model due to massive computational meshes. This paper presents a new method to measure the distribution of the static pressure and wall temperature in the narrow gap. The 300 μm-thick stainless steel plate embedded with thermocouple temperature sensors and pressure tapping holes connected with microchannels is fabricated, and the temperature and pressure measurements are calibrated through comparisons with commercial sensors. In the experimental evaluation, the 23 flat plates are stacked with a narrow gap and the sensor-embedded plate is placed in the center. Then, the stacked plate thermo-fluidic system is installed in a wind tunnel. The measurement of the static pressure and wall temperature distributions in the narrow gap is performed successfully for the increased inlet flow velocities. The static pressures are measured at five different micro tapping holes, and the measurements exhibit a standard deviation of ±3.51 Pa for the same inlet velocity. Furthermore, the wall temperatures have good agreement with the reference temperatures measured at the inlet.

Article history: This paper summarizes the results of an investigation into the environmental factors that have an indirect impact on parts quality, as well as those process variables and modeling information that have a direct impact. The effects of strength, surface hardness, roughness, and accuracy of shape, that is, qualities that users generally need to know, were evaluated with laminating direction experimentally. The 3D printing methods used in this experiment were fused deposition modeling (FDM), stereolithography apparatus (SLA), selective laser sintering (SLS), 3D printing (3DP) and laminated object manufacturing (LOM). The goal was to achieve a high standard of quality control and product quality by optimizing the fabrication process.

This work presents the possibility of the hollow core nanoparticles to improve luminance in an organic light emitting diode device. The finite difference time domain simulation estimates the effect of the hollow core nanoparticles on the external quantum efficiency of the organic light emitting diode device. The efficiency depends on the size and the volume fraction of the hollow core nanoparticles in the polymer layer, together with the refractive index and the thickness of the polymer layer. It is shown that the hollow core nanoparticles dispersed in a polymer layer can enhance the external quantum efficiency by a factor of 2.5. This work also introduces a continuous production method of the hollow core nanoparticles by using the microfluidic self-assembly of amphiphilic polymers and the layer formation dispersed with them for the rigorous light scattering.

This paper presents a novel direct fabrication method of the thin metal film RTD temperature sensor array on an arbitrary curved surface by using MEMS technology to measure a distributed temperature field up to without disturbing a fluid flow. In order to overcome the difficulty in the three dimensional photography of sensor patterning, the UV pre-irradiated photosensitive dry film resist technology has been developed newly. This method was applied to the fabrication of the temperature sensor array on a glass tube, which is arranged parallel and transverse to a main flow. Gold was used as a temperature sensing material. The resistance change was measured in a thermally controlled oven by increasing the environmental temperature. The linear increase in resistance change and a constant slope were obtained. Also, the sensitivity of each RTD temperature sensor was evaluated.

This paper presents the fabrication and performance measurement of a temperature sensor array on a flexible substrate attachable to a curved surface using MEMS technology. Specifically, the fabrication uses the well-developed printed circuit board fabrication technology for complex electrode definition. The temperature sensor array are lifted off with a matrix in a to visualize temperature distribution. Copper is used as temperature sensing material to measure the change in resistances with temperature increase. In a thermal oven with temperature control, the temperature sensor array is Characterized. The constant slope of resistance change is obtained and temperature distribution is measured from the relationship between resistance and temperature.

This paper presents a droplet-based micro chemical plant with the chemical preparation, volume-fragmentation reaction and continuous separation of product with quantitative evaluation. It consists of a cross-channel network to prepare the droplet-based chemicals, a bifurcation channel to obtain the volume fragmentation of droplet and the pelican mouth separator to extract the reaction-completed chemicals.

This article presents a new approach to measure the fluid velocity using the flow-induced vibration of a microcantilever. The gas flow sensor was fabricated using the microfabrication technology and mounted on a printed circuit board for experimental evaluation. For signal processing, a Wheastone bridge circuit was prepared. The experimental measurement of the fluid velocity was performed in the wind tunnel. The flow-induced vibration of the microcantilever was firstly visualized. Based on the power spectrum analysis, the vibrating frequency was constant at 1.173 kHz, independently of the inlet velocity. It is completely different from the conventional flow-induced vibration proportional to the inlet velocity. The peak-to-peak voltage outputs corresponding to the air velocities of 3, 4, 5 and 6 m/s were measured.

⎯ In this letter, a laterally-driven bistable electromagnetic microrelay is designed, fabricated, and tested. The proposed microrelay consists of a pair of arch-shaped leaf springs, a shuttle, and a contact bar made from silicon, low temperature oxide (LTO), and gold composite materials. Silicon-on-insulator wafers are used for electrical isolation and releasing of the moving microstructures. The high-aspect-ratio microstructures are fabricated using a deep reactive ion etching (DRIE) process. The tandem-typed leaf springs with a silicon/gold composite layer enhance the mechanical performances while reducing the electrical resistance. A permanent magnet is attached at the bottom of the silicon substrate, resulting in the generation of an external magnetic field in the direction vertical to the surface of the silicon substrate. The leaf springs show bistable characteristics. The resistance of the pair of leaf springs was 7.5 Ω , and the contact resistance was 7.7 Ω . The relay was operated at

In response to the ever increasing need for efficient management of energy consumption, there have been extensive studies on drag reduction in many types of transport systems. In this paper, we examine the reduction of skin frictional drag in a pipe with an internal surface fabricated with cavity array by using the slip obtained on a convex air bubble array. The bubble formation was observed in a microchannel by using a high-speed CCD camera with respect to time and a micro PIV characterized by measuring velocity distribution around the convex bubble. Also, to investigate the possibility of the drag reduction, the volumetric flow rate and momentum flux were compared with and without the convex air bubble array in the microchannel. The measured momentum flux was rapidly increased around the convex air bubbles, which expected the reduction of skin frictional drag. Also, the slip influence distance was determined for the different bubble heights along the microchannel. The convex air bubble with larger height provides longer slip influence distance. Finally, the cavity array was fabricated on the internal surface of a pipe. The size of the cavity array was designed 100 μm in a rectangle, and they were spaced with 150 μm. The pipe diameter was 28.4 mm, and its length was 500 mm. The pipe was installed into a test rig to evaluate the drag reduction and was experimented in the turbulent flow condition, in which Reynolds number was ranged from 40,000 to 220,000. Maximum drag reduction of 10 % was obtained in the cavity pipe, while that of the smooth pipe was shown

This paper presents the design, fabrication and testing of prestressed bimorph microbeams for applications to tunable acceleration switches. The prestressed bimorph beams are buckled due to the residual stress difference between two dissimilar films, thereby generating initial beam deflections upon fabrication. Necessary and sufficient conditions for snapping action of the deflected bimorph beam have been derived from snap-through buckling analysis. A set of SiO 2 /p + -silicon bimorph beams has been designed and fabricated in three different lengths, 800, 900 and 1000 μm. The electrostatic snap-through voltage for each microbeam has been measured as 32, 56.3 and 76.5 V, respectively. Micromechanical properties of beam materials have been measured from on-chip test structures. It is demonstrated that the three different microswitches with a 7 μg proof-mass can be applicable to acceleration switches, where threshold acceleration levels can be adjustable within the ranges 0–14, 0–35 and 0–47 g , respectively, under inter-electrode bias voltages of 0–76 V.

This paper proposes a high accuracy fabrication method for multilayer PDMS (polydimethylsiloxane) devices. Based on newly developed multi-stacking process using three-dimensional (3D) alignment marks of the concave-convex pair structures, a multilayer PDMS device was fabricated without skillful handling for alignment. Total misalignment of smaller than 10 μm is achieved for fabrication of a five-layer PDMS device. The precisely aligned multilayer structure was applied to a novel type of particle separation. By 3D secondary rotation flow in the 3D fluidic microchannel, two types of microparticles of 10 μm and 20 μm in diameter were successfully separated with high throughput.

A laterally driven bistable electromagnetic microrelay has been designed, fabricated, and tested. The working principle of the proposed microrelay is based on the Fleming's left hand rule. Silicon-on-insulator wafers are used for electrical isolation and releasing of the moving microstructures. The high-aspect-ratio microstructures are fabricated using a DRIE process. The tandem-typed arch- shaped leaf springs with a silicon/gold composite layer enhance the mechanical performances while reducing the electrical resistance. A permanent magnet is attached at the bottom of the silicon substrate, resulting in the generation of an external magnetic field in the vertical direction of the silicon substrate. The leaf springs show a bistable behavior. The resistance of the pair of leaf springs was 5.5Omega and the contact resistance was 4.7Omega. The driving voltage is measured to be plusmn0.5 V.

The in-plane digitalization of the multiphase microfluid is presented in low Reynolds number flow regime. It is achieved by manipulation of the pitch of the alternate microfluid flow and the delay distance resulting form hydrodynamics in special microchannels. The theoretical analysis derives delay distance. For the experimental evaluation, a characteristic in-plane microchannel is fabricated. Specifically, digital sorting is attempted by introducing two immiscible fluids. Also, we examine digital lamination of two miscible fluids. Finally, the digitalization is characterized qualitatively and qualitatively by using micro-PIV measurement. The short diffusion path and large contact surface obtained from digital lamination is applicable to chemical and biochemical reaction.

This paper presents a novel fabrication method of in-channel three-dimensional micromesh structures using the conventional photolithography. The micromesh was realized by exposing UV light from the backside of the SU-8 coated metal-patterned glass substrate for different angles. Numbers of exposure and irradiation angle decided the shape and the size of micromesh. Based on this technique, three different micromesh-inserted microchannel structures were fabricated. For hydrodynamic characterization, their flow resistances were measured. Finally, for the application of micro total analysis system (/spl mu/TAS), the microfilter was fabricated and its filtering property was demonstrated.