Feeding Ports Research Articles

Optimal performance comparison of the simulated moving bed process variants based on the modulation of the length of zones and the feed concentration

The VariCol and ModiCon processes are two variants of the simulated moving bed (SMB) process, characterized by the modulation of the length of zones of the chromatographic column train and the feed concentration. These features give more flexibility than the conventional operation, leading to essential improvements in the separation and purification of mixtures. The optimal performance comparison of these two variants, the hybrid formed by their combination, and the conventional SMB process are scarce in the literature. This comparison helps discover new characteristics of each single and combined operation mode and creates guidelines to select the appropriate operation mode for possible real applications. In this work, the performance comparison of the ModiCon, VariCol, ModiCon+VariCol, and SMB processes is carried out in terms of maximal throughput for specific product purity values. Particular emphasis is placed on both the ModiCon and the hybrid ModiCon+VariCol processes characteristics. A strategy for combining and optimizing the ModiCon and the VariCol processes was determined. As a case study, the enantioseparation of guaifenesin was considered. In the ModiCon process, more than two modulation subintervals did not improve the performance in the separation. The optimal pattern, based on two subintervals, has zero feed concentration in the first subinterval and the maximal concentration in the second one. The best result for the hybrid operation (ModiCon+VariCol) was reached when the feed port moves simultaneously as the SMB process switching period. The optimal throughput of the ModiCon and the ModiCon+VariCol processes was almost doubled than that of the SMB process. These performances were based on larger zones I and II and not in zones II and III as occur with the SMB and VariCol process. The throughput in the hybrid operation increases more significantly than the ModiCon process when 5 columns were considered instead of 6. The hybrid operation could be more attractive for a system with a few numbers of columns.

Dual circularly polarized series‐fed patch antenna array integrated with beam switching network

AbstractA reconfigurable patch array antenna exhibiting circular polarization as well as pattern switching capabilities is presented in this work. The proposed 2 × 2 series‐fed structure is capable of generating 11 switched beams at a resonant frequency of 2.44 GHz. The work also hypothesis an unsophisticated method polarization and radiation pattern diversity. An effective reduction from 2N to N for feed ports and from N to N/2 for phase shifters has also been reported. The design is realized on a single‐layered low‐cost FR‐4 epoxy laminate having a thickness of 1.6 mm. The performance evaluation of the fabricated prototype exhibits good agreement between the computationally evaluated and the experimentally obtained results, yielding six circularly polarized and five 45° slant polarized switched beams in two‐dimensional space with appreciably high gain, acceptable side lobe level, and decent impedance matching characteristics for all constituent ports. In this work, a simple four‐port beam switching network has been proposed to synthesize the 11 switched beams at an elevation angle of 0°, ±10° and ±21° in xoz‐plane and yoz‐plane with both circular polarizations and 45° slant polarization. It does not require any additional digital circuit or complex geometry as reported in recent works.

Design of Minimum Nonlinear Distortion Reconfigurable Antennas for Next-Generation Communication Systems.

Nonlinear effects in the radio front-end can degrade communication quality and system performance. In this paper we present a new design technique for reconfigurable antennas that minimizes the nonlinear distortion and maximizes power efficiency through the minimization of the coupling between the internal switching ports and the external feeding ports. As a nonlinear design and validation instance, we present the nonlinear characterization up to 50 GHz of a PIN diode commonly used as a switch for reconfigurable devices in the microwave band. Nonlinear models are extracted through X-parameter measurements supported by accurate calibration and de-embedding procedures. Nonlinear switch models are validated by S-parameter measurements in the low power signal regime and by harmonic measurements in the large-signal regime and are further used to predict the measured nonlinearities of a reconfigurable antenna. These models have the desired particularity of being integrated straightforwardly in the internal multi-port method formulation, which is used and extended to account for the power induced on the switching elements. A new figure of merit for the design of reconfigurable antennas is introduced—the power margin, that is, the power difference between the fed port and the switching elements, which combined with the nonlinear load models directly translates into nonlinearities and power-efficiency-related metrics. Therefore, beyond traditional antenna aspects such as port match, gain, and beam orientation, switch power criteria are included in the design methodology. Guidelines for the design of reconfigurable antennas and parasitic layers of minimum nonlinearity are provided as well as the inherent trade-offs. A particular antenna design suitable for 5G communications in the 3.5 GHz band is presented according to these guidelines, in which the specific switching states for a set of target performance metrics are obtained via a balancing of the available figures of merit with multi-objective separation criteria, which enables good control of the various design trade-offs. Average Error Vector Magnitude (EVM) and power efficiency improvement of 12 and 6 dB, respectively, are obtained with the application of this design approach. In summary, this paper introduces a new framework for the nonlinear modeling and design of reconfigurable antennas and provides a set of general-purpose tools applicable in cases beyond those used as examples and validation in this work. Additionally, the use of these models and guidelines is presented, demonstrating one of the most appealing advantages of the reconfigurable parasitic layer approach, their low nonlinearity.

Small Dual Narrowband BPF with Ultra-Rejection Band Using Grounded Stepped-Impedance Resonator

A simple technique, to design a dual narrowband bandpass filter with wide stopband performance, is introduced in this article based on a grounded stepped-impedance resonator (GSIR). The GSIR is a multi-behavior resonator. Following the even–odd analysis, the proposed GSIR is first analyzed to generate the specified center frequencies of the proposed passbands. Next, two ring-shaped stubs are electrically coupled to the low impedance part of the GSIR, using coupling space (s) and direct connection to the input/output ports to determine the filtering response. Finally, an experimental filter for 2.4 GHz wireless local area network and 3.5 GHz worldwide interoperability for microwave access (WiMAX) applications is constructed. The filtering characteristic performances of the simulation and measurement results are compared and discussed. Consequently, two narrow bandwidths, 40 MHZ at 2.4 GHz and 60 MHz at 3.5 GHz, are generated with ultra-high frequency suppression above 20 GHz. The surface area of the designed filter is about 56 mm2 terminating the feeding ports.

Wide-Stopband Substrate-Integrated Waveguide Filtering Crossovers With Flexibly Allocated Channel Frequencies and Bandwidths

Substrate-integrated waveguide (SIW) filtering crossovers featuring wide-stopband characteristics and flexibly allocated center frequencies (CFs) and bandwidths (BWs) for two intersecting channels are presented and studied. The development is devised upon a scheme of an over-mode dual-mode substrate-integrated rectangular cavity (SIRC) coupled with multiple single-mode cavities. First, by exploiting the orthogonal TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">102</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">201</sub> modes in the dual-mode SIRC, cross transmission and acceptable isolation can be obtained and implemented for the dual channels. Furthermore, by controlling the resonant frequencies and mutual couplings of the coupled cavities accordingly, especially the over-mode dual-mode SIRC, both the CFs and BWs of the two channels can be allocated flexibly. In addition, by incorporating three kinds of intrinsic spurious-mode suppression techniques, namely, the harmonic staggered technique, centered coupling windows, and offset centered feeding ports, wide-stopband characteristics can be achieved intrinsically and uniquely. Four practical design examples, including fifth-order direct-coupled and fifth-order cross-coupled SIW filtering crossovers with identical channel CFs and BWs, a third-order crossover with the same channel CFs but different channel BWs and another third-order case with different channel CFs but the same channel BWs are synthesized, designed, fabricated, and tested to demonstrate and validate the proposed collaborative design concepts.

Compact Multiport MIMO Antenna System for 5G IoT and Cellular Handheld Applications

A low-profile, compact, four-element, eight-port multiple-input--multiple-output and diversity antenna for 5G Internet of Things and cellular handheld applications is presented in this letter. This antenna structure contains four antenna elements, which are same in its configuration. The antenna ground dimensions are taken similar to a modern mobile handset, i.e., 60 mm × 120 mm. The four antenna elements are situated at four corners of antenna ground structure. Each antenna element has two feeding ports, thus making a total of eight-port antenna. A single antenna element has two feeding plates, which are placed perpendicular to one another so that they become cross polarized, thus exploiting polarization diversity, whereas spatial diversity also exists between different antenna elements. For reducing mutual coupling between different antenna ports, slots are cut in ground plane, including a small strip etched along the entire length of ground plane and rectangular slots cut in ground plane under every antenna element. The minimum bandwidth attained by all eight ports for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> < –10 dB is more than 1.4 GHz from 2.4 GHz to more than 3.8 GHz, which testify that it covers majority of frequency bands allocated for 5G sub-6 GHz spectrum. The isolation obtained between different ports has a minimum value of –13 dB, and the maximum value goes below –30 dB. For the covered frequency bands by this antenna structure, the correlation coefficient is found to be below 0.03, whereas the measured peak gain is in the range of 3.2--5 dB.

Design of Novel Flash Ironmaking Reactors for Greatly Reduced Energy Consumption and CO2 Emissions

The development of a novel ironmaking technology based on fine iron ore concentrate in a flash reactor is summarized. The design of potential industrial reactors for flash ironmaking based on the computational fluid dynamics technique is described. Overall, this simulation work has shown that the size of the reactor used in the novel flash ironmaking technology (FIT) can be quite reasonable vis-à-vis the blast furnaces. A flash reactor of 12 m diameter and 35 m height with a single burner operating at atmospheric pressure would produce 1.0 million tons of iron per year. The height can be further reduced by either using multiple burners, preheating the feed gas, or both. The computational fluid dynamics (CFD)-based design of potential industrial reactors for flash ironmaking pointed to a number of features that should be incorporated. The flow field should be designed in such a way that a larger portion of the reactor is used for the reduction reaction but at the same time excessive collision of particles with the wall must be avoided. Further, a large diameter-to-height ratio that still allows a high reduction degree should be used from the viewpoint of decreased heat loss. This may require the incorporation of multiple burners and solid feeding ports.

Performance Enhancement of Miniaturized Dual-Band Bandpass Filter

Recently a significant design technique was proposed to develop miniaturized dual-band bandpass filters using multilayered dual-mode resonator. The attitudes of these filters show good performance with 3 GHz upper rejection band. In order to improve the stopband performance of these filters, this article presents a new generation of miniaturized dual-band bandpass filters having extra transmission zero in the upper stopband. The desired transmission zero is generated by electrical physical length (lTZ) equal to a quarter-wavelength open-circuited stub resonator created from the filter structure itself. This is achieved by slipping down the input/output feeding ports from the far end connection points to the desired electrical length. To verify the proposed idea, a dual-band BPF operating at 1.9 GHz GSM and 3.5 GHz WiMax systems is designed, simulated and fabricated. The measured and simulated filter responses are in well agreed. It is observed that this filter has attenuation better than 15 dB over 5 GHz rejection band. The filter circuit area is very small of about 37mm2 terminating the feeding ports.

Wideband Frequency Agile and Polarization Reconfigurable Antenna for Wireless Applications

In this article, a polarization reconfigurable concentric circle microstrip antenna with simultaneous frequency agility has presented. The frequency agility and polarization reconfigurability have been controlled by open stub cascaded branch-line coupler (OSCBLC) feed network configuration. The −10 dB tunable impedance bandwidth of 2.0 GHz to 3.0 GHz (40%) is achieved by varying the capacitance of four varactor diodes from 4.15pF (0 V) to 0.84pF (7.5 V). These varactor diodes are fixed between the circular patch and ring. The polarization is reconfigured by directing the input RF through a single pole 4 throw (SP4 T) and routed to a single pole double throw (SPDT) switch in the feed network configuration. The right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) are realized in the antenna by exciting the feed ports with a time phase difference of ± 90°. Similarly, the vertical linear polarization (V-LP) and horizontal linear polarization (H-LP) are attained in the antenna by excited any one port through the feed network. The impedance bandwidth (1.5 GHz to 3.5 GHz) of OSCBLC feed network configuration is well-matched with the agile wide impedance bandwidth of the designed antenna. The proposed designed antenna shows good agreement between simulated and measurement results for polarization reconfigurability and frequency agility.

Design of a Coplanar Interlayer Gapped Microstrips Arrangement for Multi-Nuclei (1H, 19F, 31P, and 23Na) Applications in 7T MRI

Seven Tesla Magnetic Resonance (MR) systems can obtain high quality anatomical images using protons (1H) and can be used for multinuclear imaging and MR spectroscopy. These imaging modes can also obtain images and metabolic information using other nuclei, such as 19F, 31P, and 23Na. Here, we present an RF coil unit using a microstrip capable of resonating at four frequencies: 300 (1H), 280 (19F), 121 (31P), and 78 (23Na) MHz. The RF unit consists of a single feeding port and four lines that resonate and run a current at their respective frequency. We used the gapped microstrip concept to isolate each conducting line and interleaved the dielectric materials used for each line, thereby reducing the coupling between them. We also analyzed this design using electromagnetic (EM) simulations, and found that the quad tuned arrangement produced low coupling between adjacent current lines and achieved a uniform |B1| field in the z-y plane.

Flow field and particle motion characteristics of rotary triboelectric separator based on CFD simulation

ABSTRACT This paper studies particle motion and flow field characteristics with fly ash as an example and combine the experiments to analyze the separation process of rotary triboelectric separator in detail. Under boundary reference conditions of 22 kV plate voltage, 3 m/s feed flow, and 1815 r/min (189.95 rad/s) friction wheel speed, it simulated single-particle and particle group movement with different plate voltages and different feeding positions. Simulation of particle movement shows that particles may collide with a plate to cause serious particle mixing when plate voltage is higher. The initial velocity direction of particles is vertical downward and particles enter the separation chamber from the middle of the feeding port as much as possible to achieve better separation. The analysis of the flow field shows that the increase of the feeding airflow speed leads to a higher flow velocity inside the friction chamber and increases turbulence intensity; increases in friction wheel speed enhances flow field uniformity in the friction chamber and it is accompanied by an increase in velocity gradient; The co-flow speed mainly affects airflow field in the sorting room, the increase of co-flow speed within a certain range effectively stabilizes airflow field in the sorting room.

Azimuth-Pattern Reconfigurable Planar Antenna Design Using Characteristic Mode Analysis

In this paper, a patch antenna is proposed with reconfigurable patterns in the azimuth plane. The basic structure of the antenna is a circular patch upon which a vertical slot is etched. In addition, a row of shorting posts along the horizontal direction is placed underneath the patch. With the aid of characteristic mode analysis (CMA), reconfigurable patterns are achieved by synthesizing the currents of different modes. By switching over different sets of feeding ports, four steerable beams capable of covering the entire azimuth plane are obtained. One unique feature is that when the beam is switched to the direction orthogonal to it, the shape of the pattern will be switched accordingly. The antenna was fabricated and measured. The measured F/B ratio is close to 10 dB at 2.08 GHz, and the 3-dB beamwidth in the elevation (azimuth) plane is switchable from 82° (181°) to 190° (91°).

CFD Investigation of the In-Situ Gasification Process of Biomass in the Chemical Looping Combustion System

At present, chemical looping combustion has emerged as a promising combustion technology for carbon capture due to the inherent separation of CO2 with other flue gas components. In this work, the gas-solid reactive flow in the biomass gasification of the fuel reactor of chemical looping combustion is numerically studied via the multiphase particle-in-cell approach in the Eulerian-Lagrangian framework. After the model validations with experimental measurements, the gas-solid reactive flow behavior together with the effect of operating parameters are discussed. The results show that the nonuniform distribution of solid phase along the axial direction results from the size-induced segregation, which gives rise to the accumulation of large particles in the bottom and elutriation of fine particles. The skewed distribution of biomass residence time in the fuel reactor can be observed. The smallest carbon content exists in the region close to feeding port. Above the feeding position, the increase of carbon content but decrease of biomass mass can be observed. Compared with oxygen carrier, biomass particles have a larger dispersion coefficient. Small content of CO and H2 appears while a wide range of CO2 exists in the dense region of reactor.

Dynamics and control of loop reactors: a review

In the loop reactor (LR) the system is composed of several reactor units that are organized in a loop and the feeding takes place at one of several ports with switching of the feed port in a periodic way. In its simplest operation a pulse is formed and rotates around it, producing high temperatures which enable combustion of dilute streams. A limiting model with infinite number of units was derived. Rotating pulses, that are steady in a coordinate moving with the switch velocity, emerge in both asymptotic and discrete models when the ratio of switching to front propagation velocities is around unity. But this behavior exists over a narrow domain of this ratio. Simulations were conducted with generic first order Arrhenius kinetics. Experimental observations of simple frozen rotating pulses are reviewed. Outside the narrow frozen rotating patterns domain the system may exhibit multi- or quasi-periodic operation separated by domains of inactive reaction. The bifurcation set incorporates many ’finger’-like domains of complex frequency-locked solutions that allow to significantly extend the operation domain with higher feed temperature or concentration. Control is necessary to attain stable simple rotating frozen patterns within the narrow domains of active operation. Various control approaches that were suggested, or experimentally applied for this purpose, are reviewed. Actual implementation of combustion in LR will involve several reactants of different ignition temperatures and varying concentration. Design and control should be aimed at producing locked fronts and avoid extinction of the slower reaction.

Edge Port Excited Metamaterial Based Patch Antennas for 5G Application

Microstrip Patch Antenna is a narrowband antenna fabricated by etching the antenna element pattern in metal trace of elements like copper bonded to an insulating dielectric substrate with a continuous metal layer on the opposite side of the substrate which forms a ground plane. Electromagnetic Metamaterial is an artificial material that is made up of different types of structural designs on dielectric substrates. In this paper, a broad and elite investigation is being carried out by designing and simulating a single negative metamaterial cell comprising a square split ring resonator. This metamaterial cell depicts negative values of permeability for a specific range of frequencies. These cells show exceptionally great applications in the design of microstrip patch antenna. The substrate of the microstrip patch antenna with a ground plane is loaded with a square split-ring resonator, Conventional and proposed patch antennas are simulated, analyzed, and reported for performance comparison of its parameters. The proposed edge port feed metamaterial based Rectangular microstrip patch antenna and Circular patch antenna designed at 26 GHz resonance frequency useful for 5G applications. Both antennas are designed on RT Duroid 5880 Substrate with 2.2, dielectric constants. The parameters such as bandwidth, gain and return loss of metamaterial loaded rectangular microstrip patch antenna and Circular patch antenna increases considerably compared to conventional antennas. Comparing parameters of both antennas, the performance of the rectangular microstrip patch antenna is found to be better than circular patch antenna.

A High Isolation Dual-Polarized Microstrip Antenna for Sub-6 GHz Base Station

A dual-polarized microstrip antenna with high isolation for Sub-6 GHz (3.4- 3.6 GHz) base station application is presented in this letter. To increase isolation between two feed ports, the stacked patches are excited by double orthogonal open-ended feed lines. The proposed antenna is simulated by HFSS18.0. The simulation results show that the isolation is better than 50 dB over the whole bandwidth from 3.23 to 3.85 GHz with the cross-polarization levels less than - 30 dB when the gains are higher than 7.64 dBi for dual polarization. It’s valuable for this design method to devise mobile communication system base station antenna used in Sub-6 GHz of China Unicom and China Telecom.

Preparation and properties of metal textured polypropylene composites with low odor and low VOC

Abstract The aim of the present work is to upgrade the functionality and environmental friendliness of polypropylene (PP) by means of a blending technique. The influence of the metal pigment on the odor, volatile organic compounds (VOC) and metal texture of PP, and the effects of the extractant, adsorbent and processing technology on the odor and VOC of PP composites were studied systematically. It was found that metallic pigment significantly increased the VOC, odor, metallic texture and MFR of PP, and reduced the impact strength and elongation at break. The adsorbent and extractant can effectively reduce the VOC and odor of the PP composites. When the adsorbent and extractant contents were 0.5 and 5 wt%, respectively, the maximum reduction in the VOC and odor reached 73.6% and 1 level, respectively. When the extractant and adsorbent were used at the same time, the method of adding extractant and adsorbent from the main and the secondary feeding port respectively was significantly superior to the method of adding the extractant and adsorbent from the main feeding port together in reducing the odor and VOC of PP composites, which displayed a good synergistic effect.

Dual circular slot ring triple-band MIMO antenna for 5G applications

Abstract A Triple-band Multiple-Input-Multiple-Output (MIMO) antenna for 5G mobile terminal applications is proposed in this paper. The design comprises four-port/two resonators, each having two concentric circular slot ring radiators etched on a ground plane of size 50 mm × ${\times}$ 50 mm. The antenna is fed by perpendicularly arranged 50 Ω microstrip line feeds on the top layer. Decoupling techniques were used to suppress mutual coupling between the two resonators. The perpendicular arrangement of the feed lines and port reduces mutual coupling between the two ports and increases isolation. The antenna operates in multiple bands: 3.35–3.69 GHz, 24–28 GHz, and 37–40 GHz frequency range with central frequencies at 3.5 GHz, 26 GHz, and 38 GHz, respectively allocated for 5G. The antenna provides a gain of 2.7–7.8 dB and a radiation efficiency of 0.49–0.85 in the operating bands. Diversity performance is studied in terms of the Envelop Correlation Coefficient (ECC), Diversity Gain (DG), and Total Active Reflection Coefficient (TARC) were found to be less than 0.01, greater than 9.99 dB, and less than −10 dB respectively. The proposed antenna offers good S-parameters, voltage standing wave ratio (VSWR), TARC, radiation pattern, high gain, and low ECC. The antenna was fabricated and tested. The measured results and simulated results are in good agreement. It possesses sufficient potential for 5G mobile terminal and smart wearable applications.

Experimental Investigations on Lateral Dispersion Coefficients of Fuel Particles in Large-Scale Circulating Fluidized Bed Boilers with Different Coal Feeding Modes

The dispersion characteristics of fuel particles over the bed have always been a key consideration in the design of fluidized beds. However, the lateral fuel dispersion coefficients (Dsr) reported in the previous literature widely ranged from 10−4 to 10−1 m2/s, which were hard to be directly applied in large-scale CFB (circulating fluidized bed) boilers with wider bed width (close to 30 m) and variable coal feeding modes. To solve this problem, field tests were conducted on the first 600 MW CFB boiler in this paper, and the distributions of flue gas composition and flue gas temperature were obtained near the coal feeding port under four working conditions. The dispersion characteristics of fuel particles were analyzed in detail combined with the dispersion model. In addition, a new method based on bed heat balance was also proposed to estimate Dsr and applied in a 300 MW CFB boiler with a different coal feeding mode. The results revealed that Dsr through the local heat balance method ranged from 0.10–0.35 m2/s, which were 9–18% higher than the values through the dispersion model. Compared with the coal feeding port immersed in the bed, Dsr of the fuel particles fed into the splash zone increased by about 34.7%. Dsr under the coal feeding mode of a screw feeder with pressurized air ranged from 0.12–0.16 m2/s, which were lower than Dsr under the coal feeding method of importing fuel into circulating ash. The method and results in this paper could expand the applicability of fuel dispersion, and provide the most direct guidance for the design and optimization of coal feeding ports in large-scale CFB boilers.

Design and Measurement of a Ku-Band Pattern-Reconfigurable Array Antenna Using 16 O-Slot Patch Elements With p-i-n Diodes

A novel Ku -band pattern-reconfigurable array antenna is designed and experimentally tested, which is able to electronically form various radiation patterns, including a single pencil beam, dual beams, quad beams, and a single fan beam. It consists of 4 × 4 probe-fed O-slot patch elements. Two p-i-n diodes are integrated on the O-slot of each element, and by alternatively activating one of the p-i-n diodes, the direction of the excitation current is reversed. Hence, the element is able to generate two-phase states with 180° phase difference. In order to properly excite the elements, a stripline power dividing network with a waveguide feeding port is designed. Furthermore, an antenna prototype is fabricated and measured. The measured gain of the single pencil beam is 15.0 dBi at 12.5 GHz, and the measured 1 dB gain bandwidth is 9.6% (11.8–13.0 GHz). The simulations and measurements of various beam patterns agree very well, which successfully verify the dynamic pattern-reconfigurable capability of the proposed array design.