Slit Gap Research Articles

Active control of polarization-dependent terahertz surface plasmonic wave excitation using coupled graphene-metal hybrid metasurfaces

Active control of terahertz surface plasmonic wave (SPW) intensity in the propagation direction holds substantial significance for advanced terahertz functional devices. In this study, we propose a graphene-metal hybrid split-ring slit resonator (SRSR) array metasurfaces and employ the concept of electromagnetically induced transparency (EIT) to achieve excitation of asymmetric SPWs under various polarization states. By individually integrating two graphene ribbons into the two split-ring slit gaps and applying different bias voltages, we observed a gradual transition in the excitation behavior of asymmetric terahertz SPWs, ultimately resembling that of a single SRSR. Near-field simulations reveal that this phenomenon is attributed to the short-connection effect of graphene. Our proposed graphene-metal active hybrid metasurface introduces a novel approach to realize active SPWs devices, holding potential applications in terahertz on-chip communication.

Molecular simulation of water permeation and salt rejection for MoS2 nanoslit membranes

Molybdenum disulfide (MoS2) layer-stacked membranes have gained considerable attention due to their chemical stability and water permeability in desalination processes. However, molecular transport across slit gaps between edge-to-edge MoS2 nanosheets remains unexplored. It is suspected that edge chemistry in MoS2 slits could be important in the MoS2 desalination membranes. Herein, molecular simulations were performed to investigate water permeation and salt rejection for the MoS2 slits with different edge patterns and slit spacings. It is demonstrated that MoS2 nanoslits could realize high water permeation and efficient ion rejection, in particular, the SS edge slit shows excellent desalination efficiency. The water permeation across MoS2 slits could be attributed to the confined water structures and the surface slips on the edge patterns, both of which are influenced by different surface interactions. The free energy landscapes were simulated to characterize the thermodynamics resistance for ions passing through MoS2 nanoslits. The salt rejection is the combining contributions from the ion hydration interaction and the MoS2 slit interaction, wherein the Coulombic interaction provides the critical influence. Overall, our work will hopefully pave the way for design in applications of MoS2 desalination membranes.

56‐1: Invited Paper: Ultra‐high Frame Rate ADS LCDs

In recent years, LCD end‐users are putting forward higher and higher requirements for dynamic picture display realism. With the increase of display panel refresh rate, dynamic picture fidelity has a significant improvement. The extremely high refresh rate has become one of the most important indicators of high‐end display panels, especially for video game usage scenarios. However, the increase in refresh rate is a challenge to the drive capability of LCD semiconductor TFTs (Thin Film Transistor), the response time of liquid crystal, and the transmission of high‐frequency signals, resulting in the maximum refresh rate of high‐refresh‐rate displays currently on the market still at 240 ~ 300 Hz. In this paper, we solve the display distortion due to low charging ratio at ultra‐high refresh rate by improving GOA（Gate Driver on Array） driver circuit and applying high stability and high mobility bilayer oxide semiconductor technology. At the same time, the 1ms GTG (Gray to Gray) response time is achieved by testing and optimizing the pixel slit angle and cell gap of ADS (Advanced Super Dimension Switch) LCD, ensuring no image trailing at refresh rates up to 600 Hz. Then the anti‐electromagnetic interference ability of high‐speed signal is improved by high‐speed signal transmission quality enhancement technology. Through the application of the above technologies, we have developed the ultra‐high refresh rate IT display panel products such as 600Hz frame rate FHD NB LCD and 500 Hz FHD MNT LCD. And the 16.0” WUXGA 600Hz ADS LCD achieves the highest CMR 9000 rating in VESA latest dynamic picture CMR certification.

МНОГОСТУПЕНЧАТЫЙ ЭЖЕКТОР

A device for ejecting several streams based on the flow of a stream in a slit gap and designed for mixing liquid and gaseous media is considered

ПРОЕКЦИОННАЯ АНАТОМИЯ ЧАСТЕЙ ЖЕЛУДКА ПЛОДА В 16-22 НЕДЕЛЬ ОНТОГЕНЕЗА ЧЕЛОВЕКА

The formation of the stomach and its functional maturation occupy a significant period of ontogenesis, in which the process of complex interaction of the structural elements of the primary intestine takes place. For periand neonatologists, ultrasound diagnostics doctors, 16-22 weeks of pregnancy are especially important. There is no information on the topography of the human fetal stomach in the scientific literature. During the study, new information was obtained on the topography of parts of the stomach at 16-22 weeks of ontogenesis. The features of the syntopy of parts of the stomach include unexpressed contact with the diaphragm, almost complete closure of the anterior wall by the lobes of the liver, contact of small curvature with the caudate lobe of the liver, lack of contact with the left kidney, tight coupling with the left adrenal gland. The hepatic-duodenal, hepatic-gastric, gastro-diaphragmatic and gastro-splenic ligaments are quite well differentiated. The forming pre-pancreatic and omentum bags are determined, which at this stage of ontogenesis are slit gaps, practically devoid of air spaces. However, the shape and position of the pre-ventricular sac at 16-22 weeks of intrauterine development do not coincide with the boundaries of that of an adult. During the study period, the levels of the esophagus-stomach transition were also determined in the fetus, protectively located in the Th IX body area, at the height of the Th VIII rib, along the left circumflex line. The stomach of the fetus at 16-17 weeks of development is located at the level of Th VII (lower edge) by Th XI (lower edge), by 22 weeks the stomach drops to the level of Th VIII by L I (upper edge). A feature of skeletotopy of the stomach is a more stable location at the specified time of human ontogenesis, where the bottom of the stomach is determined in the projection Th VIII , the cardiac part at the level of Th VIII -Th IX , the body of the stomach -Th X-XI and the pyloric part at the height of Th XI-XII . The pre-pancreatic and omentum bags at week 16-22 of ontogenesis are slit-like gaps. Horizontal and sagittal cuts allow us to determine the characteristic features of syntopia and skeletotopia of the stomach. The data obtained supplement the available information on the age-related anatomy of the stomach of newborns, children, and adults, and are also of interest to anatomists, topographers, neonatologists, ultrasound diagnostics doctors, pediatricians and fetal surgeons.

Air-knife design for improved drying efficiency in manufacturing flat-panel displays

Abstract With the growing demand for flat-panel displays (FPDs), the size and production conveyance speed of glass are increasing to improve productivity. Improvement of productivity, speed, and efficiency in the drying process used in FPD manufacturing has become an important issue. Therefore, this study aims to improve the drying efficiency by optimizing the primary design variables of an air knife, the most common FPD drying system, through numerical analysis. To optimize the air-knife design, the feasible optimal values were fixed for the slit gap (0.15 mm) and glass gap (1.5 mm), and the optimized dimensions were determined by considering the nonsymmetric distance (0.5 mm) and installation angle (15°) of the end geometry of the air knife channel. The optimized air-knife design improved the drying efficiency by approximately 30% compared to that of the existing system; therefore, it can increase the productivity of the FPD manufacturing process.

Spatial distribution and transport mechanism of electrons in large and powerful inductively coupled plasma sources with Faraday shield

A large and powerful radio frequency (RF) inductively coupled plasma (ICP) source with a Faraday shield (FS) has been investigated by a 3D fluid model, consisting of a plasma module and an electromagnetic field module. Effects of the structure of the FS, the RF current, and the gas pressure on the spatial distributions of plasma parameters including the electron density, electron temperature, and electron potential barrier are investigated systematically. The results show that the FS has a great influence on the spatial distribution and transport mechanism of electrons. The electron density has a maximum value at the center of the ICP source and declines sharply near the FS. Furthermore, it decreases obviously with the decreasing slit width, due to the electron transport mechanism, which is directly related to the electron potential barrier and electron temperature. In addition, the electron density increases with the RF current and gas pressure; it is noteworthy that the stronger induced electric field heating exists at the slit gap under high RF current that makes the electron temperature increase. The data obtained in this paper could lead to a deeper insight into the characteristics of ICP sources, which is extremely essential for optimizing the FS structure and designing large and powerful radio frequency ICPs in the future.

Combustion Characteristic inside Micro Channel Combustor

Small-scale electronic devices require long hours’ operation and fast charging time. Potential technology to support requirement of small-scale electronic device is micro scale combustor. Unfortunately, micro scale combustion is prone to combustion instability. Therefore, objective of this study is to investigate the combustion characteristics, mechanism that stabilize the flame and combustor performance of the 2-D microchannel combustor with bluff body having various slit percentages gap. Two-dimensional computational domain with the height and length of the channel H = 1 mm and L = 16 mm is used respectively. The height of the bluff body is 0.5 mm and located at 2 mm from the inlet. The slit gap percentage varied in this study is 0% to 70%. The results show that the combustion characteristic such as stable flame, wavy flame, blow-off, and flame split into two parts is significantly influenced by the slit gap percentage. Flame is moving downstream and blow-off at the slit percentage of 10% to 25%. At the slit percentage of 30%, the flame zone moves towards the upstream due to the secondary vortex that exists behind the bluff body as slit gap increases and pushes the flame upstream. The reaction zone is split into two parts at 60% and 70% slit gap percentage. It is due to the incoming fresh mixture of CH4/air mixture flows through the slit and cuts the flame zone. It is also found that by increasing inlet velocity beyond 2.0 m/s, the flame becomes unstable and leads to blow-off as increase in equivalence ratio up to 1.0.

Hydrodynamic response time of magnetorheological fluid in valve mode: an initial study

The transient behaviour of magnetorheological (MR) damper is a very important parameter affecting the performance of this technology in modern semi-actively controlled suspension systems. Currently, the transient behaviour of the MR damper is limited by dynamics of the MR fluid (MRF) itself. The significant part of MRF response time is a hydrodynamic response time which is connected with transient rheology and development of velocity profile in the slit gap. In this paper, the method for measuring the hydrodynamic response time of MRF operating in valve mode is presented. The hydrodynamic response time of MRF-132DG achieved value of τ90 = 0.78 ms for H = 17.5 kA/m a value of τ90 = 0.65 ms for H = 34 kA/m for given geometry of gap. The difference between model and experiment is lower in higher yield stresses of MRF.

Tactile Perception Based on Injected Vibration in Soft Sensor

Tactile perception using vibration sensation helps robots recognize their environment's physical properties and perform complex tasks. A sliding motion is applied to target objects to generate tactile vibration data. However, situations exist where such a sliding motion is infeasible due to geometrical constraints in the environment or an object's fragility which cannot resist friction forces. This letter explores a novel approach to achieve vibration-based tactile perception without a sliding motion. To this end, our key idea is injecting a mechanical vibration into a soft tactile sensor system and measuring the propagated vibration inside it by a sensor. Soft tactile sensors are deformed by the contact state, and the touched objects' shape or texture should change the characteristics of the vibration propagation. Therefore, the propagated-vibration data are expected to contain useful information for recognizing touched environments. We developed a prototype system for a proof-of-concept: a mechanical vibration is applied to a biomimetic (soft and vibration-based) tactile sensor from a small, mounted piezoelectric actuator. As a verification experiment, we performed two classification tasks for sandpaper's grit size and a slit's gap widths using our approach and compared their accuracies with that of using sliding motions. Our approach resulted in 70% accuracy for the grit size classification and 99% accuracy for the gap width classification. These results are comparable to or better than the comparison methods with a sliding motion.

Acoustic metasurfaces for efficient matching of non-contact ultrasonic transducers

Air-coupled ultrasonic techniques based on rapid and contactless inspection are useful for various applications, such as ranging finding, surface profile measurement, and non-destructive evaluation. However, impedance matching issues between air and piezoelectric materials lead to technical limitations, such as imaging resolution and penetration depth. In order to mitigate these problems, we utilize acoustic metasurfaces consisting of periodic concentric ring arrays with narrow slits and tiny air gap spacers. Narrow slits induce Fabry–Pérot resonance with respect to slit thickness, and tiny gap spacers generate half-wave resonance with respect to the period. Here, we utilize the coupled resonance combined with slit resonance and gap resonance. These coupled resonances lead to efficient impedance matching of airborne sound from ultrasonic transducers. Thus, these metasurfaces lead to a broadband sound pressure level gain in the frequency range of 0–80 kHz. Enhanced pulse signals using the pulse-echo and through-transmission ultrasonic techniques are achieved.

Performance Analysis of Novel Multi-band Monopole Antenna for Various Broadband Wireless Applications

This study investigates a novel concept of using slot and Coplanar Waveguide fed antenna to obtain multiband operation. The compact antenna includes a star monopole patch with a slit gap and a Star-shape slot on the patch as the radiating part and Dual Square shaped slots on the material as the ground plane. The presentation of techniques in the star-shaped patch and ground plane expands the total length of the current path. This increasing makes the multiband antenna to operate at 4.9 (WLAN), 5.9 (upper WiMAX), 8.2 (satellite TV), 11.8 (X-band) and 17.7 GHz (Ku-band), respectively. The antenna has a physical dimension of 0.32lambda_{0} times 0.24lambda_{0} times 0.01lambda_{0} = (20 times 15 times 1) mm3, at the minimum frequency of 4.9 GHz. The proposed configuration operates at 4.9, 5.9, 8.2, 11.8 and 17.7 GHz with bandwidth (S11 < −10 dB) of about 90%, 74.7%, 53.8%, 8.4% and 4.7%, respectively for simulation part. The antenna exhibits measured bandwidth (S11 < −10 dB) of about 108%, 84%, 64%, 9%, and 7% at resonant frequencies of 4.69, 6.03, 7.99, 11.88, and 17.53 GHz, respectively. The stability of the radiation features, VSWR < 1.5 and good agreement impedance are noticed across the operating bandwidth of the multiband antenna.

A Characteristic Feature of Pressure Formation in the Gap Between Rotating Eccentrically Located Cylinders

The results of theoretical and experimental investigations of pressure distributions in a shear laminar flow between rotating eccentrically located cylinders are presented. It is shown that a change in the pressure in the slit gap is attributed to two mechanisms: to the "wedge effect" from the eccentrically located rotating tenon in the bearing and to the heat supply due to the adiabatic change of the volume, dissipative processes, and heat transfer.

Dynamic Analysis of a Micro Beam-Based Tactile Sensor Actuated by Fringing Electrostatic Fields.

A new kind of fringing electrostatic actuation mode is developed. In this new actuation mode, the expression of fringing electrostatic force is found. The nonlinear dynamic analysis of this new actuation mode is presented by using the Method of Multiple Scales. An experiment is designed to observe the dynamic behaviors of this structure. It is observed that the resonance frequency rises with the increase of the initial displacement and the decrease of the slit gap; a smaller slit gap makes marked change of the resonance frequency in the same range of the initial displacement; the increase of the vibration amplitude is linear with the increase of the initial displacement; the fringing electrostatic force has a larger impact on the frequency response of the nonlinear vibration when the initial displacement, the beam length and the actuated voltage are larger. This new fringing electrostatic actuation mode can be used in a micro tactile sensor. The results of dynamic analysis can provide support for sensor design. Based on the dynamic investigations into the micro cantilevered beam actuated by fringing electrostatic force; three usage patterns of the sensor are introduced as follows. Firstly, measuring resonance frequency of the micro beam can derive the initial displacement. Second, the initial displacement can be derived from vibration amplitude measurement. Third, jump phenomenon can be used to locate the initial displacement demand.

Effect of Oil Supply Pressure on the Force Coefficients of a Squeeze Film Damper Sealed With Piston Rings

Squeeze film dampers (SFDs) aid to both reduce rotor dynamic displacements and to increase system stability. Dampers sealed with piston rings (PR), common in aircraft engines, are proven to boost damping generation, reduce lubricant flow demand, and prevent air ingestion. This paper presents the estimation of force coefficients in a short length SFD, PR sealed, and supplied with a light lubricant at two feed pressures, Pin-1 ∼ 0.69 barg and Pin-2 ∼ 2.76 barg, i.e., low and high. Two pairs of PRs are installed in the test SFD, one set has flow conductance CS1 = 0.56 LPM/bar, whereas the other pair has CS2 = 0.89 LPM/bar. The second set leaks more as it has a larger slit gap. Dynamic load tests show that both dampers, having seal flow conductances differing by 60%, produce damping and added mass coefficients of similar magnitude, differing by at most 20%. Other experiments quantify the effect of lubricant supply pressure, Pin-1 and Pin-2, on the dynamic film pressure and force coefficients of the PR-SFD. The damper configuration with CS1 and operating with the high Pin-2 shows ∼20% more damping and added mass coefficients compared with test results for the damper supplied with Pin-1. Film pressure measurements show that the air ingestion and oil vapor cavitation coexist for operation at the low Pin-1. Computational predictions accounting for the feed holes in the physical model agree with the experimental coefficients. On the other hand, predictions from classical formulas for an idealized damper geometry, fully sealed at its ends, largely overpredict the measured force coefficients.

REGULAR SPRAY TYPE TIPS IMPROVEMENT TO REDUCE SEDIMENTS IN THE MASS-EXCHANGE APPARATUS

The article is devoted to the study of column apparatus contact devices and the creation of effective attachments for gas - liquid systems. According to the results of the studies, taking into account the updated data on hydraulic resistances, a new regular nozzle for mass transfer processes has been developed, which effectively works in polluted envi- ronments. In the developed nozzle, the rows of elements with the pitch refined relative to each other and with the slit gaps between the baffle plate in the corner elements are optimally selected. Experimental studies were carried out on the developed laboratory bench, the structural elements of which are made of Plexiglas and arranged at a certain angle to each other. Studies of the liquid and gas phases allowed to establish the numerical values of the smallest hydraulic resistance among the angle nozzles. On the basis of experiments, the viability of the created corner-type struc- tures, which provides conditions for reducing sediments, is proved. On the basis of aero-hydrodynamics laws, physical and numerical models of flows in the apparatus with regular nozzles of various types have been developed taking into account the deposition of contaminants. Experimental studies were carried out on the physical model in order to determine the liquid entrainment, dynamic holding capacity and resist- ance coefficient, model verification and parameters of a regular corner nozzle with U-shaped bump stops optimization were performed to ensure self-cleaning of mass transfer elements, which allowed for optimal func- tioning of the column apparatus with a minimum level of deposits. The parameters characterizing the stable nozzle operation and ensuring the self-cleaning of its elements from mechanical and paraffin-resin deposits are established, which made it possible to increase the interrep- air time of the mass-exchange apparatus.

ON THE PROBLEM OF VISCOUS INCOMPRESSIBLE FLUID FLOW IN A FLAT CONICAL SLOTTED CHANNEL

A precision pair operating under misalignment conditions, i.e. at a distortion of mobile elements of contactless consolidations is analyzed. The fl ow of a viscous incompressible fl uid in a fl at conical slit gap is investigated. Since the boundary-value problem does not have an exact solution, an approximate analytical solution was found in the work that does not depend on boundary conditions. The equations of motion of a fl uid are solved in the Navier-Stokes form by the method of small perturbations. The hydrodynamic parameters of a viscous fl uid as it moves through a conical slit gap are determined. The profi le of the velocity of the fl uid in the form of the sum of a pressure fl ow with a constant pressure drop and fl ow due to the oscillation of the channel wall is constructed. Graphic illustrations are given with high and low frequency limits of oscillations.

Phi Shape UWB Antenna with Band Notch Characteristics

In this paper a novel band notch antenna in UWB frequency range is designed using split rings. Split rings are overlapped with designed monopole to give phi shape. The slit gap gives band-notch operation from 5.1GHz to 6.29GHz and from 4.94GHz to 5.91GHz for SPSSR and SPSCR antennas respectively. Simulated and measured results are in good agreement.

Efficient electrode configuration for electro-conjugate fluid flow generation with dibutyl decanedioate: Experimental and theoretical investigation

Electro-conjugate fluid (ECF) is a functional fluid that can generate a high-power flow induced by a high direct-current voltage. While ECF has been used in various fields, including mechanical, chemical, and biomedical systems, its underlying principles have not been sufficiently understood to be applicable to ECF system design, and the lack of theoretical models hampers further applications of ECF. This study aims to investigate underlying principles of ECF flow generation with a rectangular-slit electrode pair. By analyzing the effect of electrode configuration on the flow generation, this paper proposes a theoretical model for electrode design for efficient flow generation. The proposed model has been validated by comparing the simulation results with the visualized characteristics from flow experiments. The results show that the flow rate can be controlled by changing the electrode configuration with the maximum flow rate with the rectangular-slit electrode gap of 1.0 mm and the slit electrode gap of 5.0 mm.

Diffusion of Supercritical Fluids through Single-Layer Nanoporous Solids: Theory and Molecular Simulations.

With the advent of graphene material, membranes based on single-layer nanoporous solids appear as promising devices for fluid separation, be it liquid or gaseous mixtures. The design of such architectured porous materials would greatly benefit from accurate models that can predict their transport and separation properties. More specifically, there is no universal understanding of how parameters such as temperature, fluid loading conditions, or the ratio of the pore size to the fluid molecular diameter influence the permeation process. In this study, we address the problem of pure supercritical fluids diffusing through simplified models of single-layer porous materials. Basically, we investigate a toy model that consists of a single-layer lattice of Lennard-Jones interaction sites with a slit gap of controllable width. We performed extensive equilibrium and biased molecular dynamics simulations to document the physical mechanisms involved at the molecular scale. We propose a general constitutive equation for the diffusional transport coefficient derived from classical statistical mechanics and kinetic theory, which can be further simplified in the ideal gas limit. This transport coefficient relates the molecular flux to the fluid density jump across the single-layer membrane. It is found to be proportional to the accessible surface porosity of the single-layer porous solid and to a thermodynamic factor accounting for the inhomogeneity of the fluid close to the pore entrance. Both quantities directly depend on the potential of mean force that results from molecular interactions between solid and fluid atoms. Comparisons with the simulations data show that the kinetic model captures how narrowing the pore size below the fluid molecular diameter lowers dramatically the value of the transport coefficient. Furthermore, we demonstrate that our general constitutive equation allows for a consistent interpretation of the intricate effects of temperature and fluid loading conditions on the permeation process.