Conventional Arrangement Research Articles

High extinction ratio electromagnetically induced transparency analogue based on the radiation suppression of dark modes

A high extinction ratio (ER) electromagnetically induced transparency (EIT) analogue based on single-layer metamaterial is designed and experimentally demonstrated in this paper. This design involves four mirror-like symmetrically coupled split ring resonators (SRRs) that exhibit a bright-dark-dark-bright mode configuration. The EIT-like effect is realized by coupling between the bright resonators and dark resonators. The high ER feature is achieved from the suppression of radiative losses, due to opposite directions of electric and magnetic dipoles of two dark modes in the unit cell. Classical coupled resonator model is used to theoretically analyze the device transmission performances and to characterize parameter influence of the ER. Both numerical simulation and experiment results demonstrate that the ER of this device can reach more than 21 dB, which is 11 dB higher than that of conventional bright-dark coupling SRR arrangement. Finally, the potential multi-channel sensing utility of this device is demonstrated to show the importance of high ER feature.

Observation of the de Vries behavior in SmA* phase of a liquid crystal using polarised Raman scattering and infrared spectroscopy.

Two approaches exist in the literature for describing the orientational distribution function (ODF) of the molecular directors in SmA* phase of liquid crystals, though several models are recently proposed in the literature for explaining the de Vries behaviour. These ODFs correspond to either the conventional unimodal arrangements of molecular directors arising from the mean field theory that leads to the broad or sugar-loaf like distribution or to the "diffuse-cone-shaped" type distribution proposed by de Vries. The hypothesis by de Vries provides for a realistic explanation as to how at a molecular level, a first-order SmA* to SmC* transition can occur where the uniform molecular director azimuthal distributions condense to values lying within a narrow range of angles; finally these condense to a single value while at the same time ensuring a little or no concomitant shrinkage in the layer spacing. The azimuthal distribution of the in-layer directors is probed using IR and polarized Raman spectroscopic techniques. The latter allows us to obtain the ODF and the various order parameters for the uniaxial and the biaxial phases. Based on the results of these measurements, we conclude that the "cone-shaped" (or volcano-shaped) de Vries type of distribution can most preferably describe SmA* where "a first-order phase transition from SmA* to SmC*" and a low layer shrinkage can both be easily explained.

Direct Drive Linear Generator Designs with Aluminium Spacer and Alternate Slot Winding for Wave Energy Conversion System

This paper presents the study on direct drive linear generator designs with aluminium spacer and alternate slot winding for wave energy conversion system . The study involved the development of permanent magnet linear generator designs with the variation on aluminium spacer utilization as part of magnet assembly and alternate slot winding usage instead of conventional winding arrangement. The proposed designs were simulated using Finite Element Method (FEM) software to attain the results on flux distribution, air-gap flux density and open circuit results. The total weight and material cost of each design were also estimated. These results are significant in finding the acceptable design’s alternatives to counter the need of huge and heavy linear generator in wave energy converter system. Comparative studies on simulation results and calculated data were conducted between the alternative and conventional design. It is found out that alternate slot winding design improves the performance of conventional design with no impact on design’s weight and material cost while aluminium spacer design yields more significant negative results on the performance than the positive effects in term of design’s weight and material cost.

Modeling of Buckled Reinforcing Bars Including Effect of Lateral Expansion of Concrete Core

Inelastic bar buckling in RC column is a complicated behavior due to the effects of slenderness ratio, concrete core expansion and constraint of concrete cover. Based on the equilibrium of a plastic mechanism with distributed lateral forces acting on buckled longitudinal bar, a nonlinear cyclic average stress–strain relationship is developed to simulate the effects of concrete core expansion. The average stress reduction coefficient Ω 2 is introduced in the proposed model to compensate for the effects of concrete core expansion with respect to the Gomes–Appleton model. Ω 2 − ɛ s (where ɛ s is the average strain of buckled bar) relationships of four conventional reinforcements arrangement of rectangular RC column sections are obtained by revising the expression of the parameter for calculating equivalent lateral force of concrete core expansion. Critical strain ɛ s,cr is proposed to identify the distribution of the equivalent lateral force acting on the buckled bars, where ɛ s,cr is the axial compressive average strain of reinforcing bar corresponding to the limit state of steel bar separating from concrete core. The influence of concrete core expansion can be estimated based on the value of Ω 2 when ɛ s is equal to ɛ s,cr under monotonic compression. In the case study, two average stress–strain hysteresis curves of buckled longitudinal bars are calculated and compared to identify the influence of concrete core expansion on buckling behavior of bar in RC column.

Potential and limitations of power generation via chemical looping combustion of gaseous fuels

Pressurized chemical looping combustion (CLC) was studied with regard to its potential for power generation from gaseous fuels, such as natural gas. A process simulation model was set up for a simplified gas turbine combined cycle (GTCC) around a pressurized CLC reactor system and studied with respect to process parameters influencing electric efficiency. The process model is based on typical large scale GTCC arrangements with a gas turbine topping cycle and a heat recovery steam generator unit (HRSG). The results are compared to conventional GTCC process with similar arrangement and process parameters. It was found that the CLC process comes along with considerable technological limitations for the efficiency of the combined cycle: (i) turbine inlet temperature is limited by the oxygen carrier material, (ii) pressure drop of CLC AR path increases the required air compression work, and (iii) the requirement for low pressure steam for gas-sealing between air reactor and fuel reactor reduces the efficiency of the steam cycle. These effects limit the achievable net electric efficiency to values below 45%, which is similar to what could be reached with atmospheric pressure CLC in a conventional steam cycle power plant arrangement (e.g. Benson-type steam generator). The gas turbine inlet temperature (TIT) was identified as the greatest limitation to the process, the pressure ratio has to be reduced accordingly to maintain sufficient exhaust gas temperatures for the HRSG, which limits the efficiency potential of the gas turbine. As a conclusion, when it comes to power generation from gaseous fuels, these limitations will need to be resolved to make CLC technology competitive to conventional GTCC power plants combined with post combustion CO2 capture technologies.

Numerical study of the influence of tube arrangement on the flow distribution in the header of shell and tube heat exchangers

The behavior of the fluid inside the internal circulation system of a shell and tube heat exchanger is complex due to the influence of many factors. The flow distribution has a significant influence on the performance of fluidic apparatus such as shell and tube heat exchangers. The non-uniformity of the flow distribution reduces the efficiency of the process. The influence of tubes arrangements on the flow distribution is presented using CFD simulations. In this study, four arrangement types are considered. The present results are in good agreement with those of the literature. The obtained results show that the arrangement of the tubes has a significant influence on the flow distribution. It was concluded that the flow distribution of 60° arrangement exhibits better uniformity compared to the conventional arrangement (90°) by 21%. The 45° arrangement gives good uniformity of pressure distribution compared to the other arrangements.

Vertically stacked capacitive tactile sensor with more than quadrupled spatial resolution enhancement from planar arrangement

In this study, the spatial resolution of a capacitive tactile sensor was enhanced more than fourfold without sacrificing the sensitivity and functionality of the sensor, compared with conventional sensors with a planar capacitance arrangement. Through the vertical stacking of two capacitors with a shared electrode, the spatial resolution was at least doubled in both x- and y-directions, and the overall density of the sensing unit was more than quadrupled for arbitrary application sizes. In addition to shear angle detection, sensing demonstrations were performed on the normal and shear forces with theoretical designs, numerical evaluations, and empirical examinations. The proposed capacitive tactile sensor has a simplified manufacturing process and an efficient detection method realized by the shared electrode, in addition to the enhanced spatial resolution. This novel design can be applied to automatic robots for grasping tiny objects because the spatial resolution can be enhanced by simply replacing the four capacitors in a conventional planar arrangement with two vertically stacked capacitors as a universal solution.

Computational study of Staggered and Double Cross Flow Heat Exchanger

The preliminary findings of a comparative study of heat transfer rate and pressure drop between conventional staggered flow and double cross flow heat exchanger is reported. Excepting for the tube arrangements, the shell and tube dimensions, materials and inlet conditions are retained the same for the two configurations. While in the conventional arrangement, adjacent rows of tubes are normal only to the fluid flow in the shell, in the double cross-flow arrangement, they are normal to both fluid flow direction in the shell as well as to each other. Shell dimensions are 100 cm × 20 cm × 20 cm and tube outside and inside diameters are 1 cm and 0.8 cm. The shell and tube materials are steel and copper. Water and air were considered as tube and shell side fluids respectively, with an overall arrangement of parallel flow. The tube flow Reynolds number was fixed at 2200 and the shell flow Reynolds number was varied from 20 to 120 in the laminar regime and 360 to 600 in the turbulent zone. The study reveals that the proposed configuration gives a maximum increase of about 27 per cent in the heat transfer rate per unit pressure drop over the conventional one.

Speed and Position Estimator of Dual-PMSM for Independent Control Drives using Five-Leg Inverter

<p>Nowadays, A lot of industry requires Multi Motor System (MMS)<strong> </strong>applications such as propulsion and traction power, HEV, conveyer and air-conditioner. The Conventional arrangement for MMS usually done by cascading the motors drives which each drives has individual inverter. Part of MMS, Dual-Motor drives fed by a single inverter is being paid attention by the researchers. Dual-motor drives using a single three-leg inverter<strong> </strong>has its limitation in the case of different operating conditions and independent speed control requirement. Therefore, dual-Motor drives using a single Five-leg Inverter (FLI) was proposed for independent control for both motors. In PMSM drives, the information of the feedback speed and rotor angular position is compulsory for variable speed drives. Conventional solution is by using speed sensor which will increase size, cost, extra hardwire and feedback devices, especially for the case of dual-PMSM drives. The best solution to overcome this problem is by eliminating the usage of speed and position sensors for Dual-motor drives. This paper presents a new sensorless strategy using speed and position estimator for Independent Dual- Permanent Magnet Synchronous Machine (PMSM) drives which utilize Five-Leg Inverter (FLI). The proposed strategy is simulated using MATLAB/Simulink to evaluate the overall motor drive performance. Meanwhile the experimental set-up is connected to dSPACE 1103 Board. The experimental results demonstrate that the proposed estimator is successfully managed to control the Dual-PMSM drives for variation of speed and for different direction applications.</p>

Optimization of Camera Arrangement Using Correspondence Field to Improve Depth Estimation

Stereo matching algorithms attempt to estimate depth from the images obtained by two cameras. In most cases, the arrangement of cameras (their locations and orientations with respect to the scene) is determined based on human experience. In this paper, it is shown that the camera arrangement can be optimized using the concept of correspondence field (CF) for better acquisition of depth. Specifically, this paper demonstrates the relationship between the CF of a pair of cameras and depth estimation accuracy and presents a method to optimize their arrangement based on the gradient of the CF. The experimental results show that a pair of cameras optimized by the proposed method can improve the accuracy of depth estimation by as much as 30% compared with the conventional camera arrangements.

Light scattering in a medium with fluctuating gyrotropy: Application to spin-noise spectroscopy

The spin noise signal in the Faraday-rotation-based detection technique can be considered equally correctly either as a manifestation of the spin-flip Raman effect or as a result of light scattering in the medium with fluctuating gyrotropy. In this paper, we present rigorous description of the signal formation process upon heterodyning of the field scattered due to fluctuating gyrotropy. Along with conventional single-beam experimental arrangement, we consider here a more complicated, but more informative, two-beam configuration that implies the use of an auxiliary light beam passing through the same scattering volume and delivering additional scattered field to the detector. We show that the signal in the spin noise spectroscopy arising due to heterodyning of the scattered field is formed only by the scattered field components whose wave vectors coincide with those of the probe beam. Therefore, in principle, the detected signal in spin noise spectroscopy can be increased by increasing overlap of the two fields in the momentum space. We also show that, in the two-beam geometry, contribution of the auxiliary (tilted) beam to the detected signal is represented by Fourier transform of the gyrotropy relief at the difference of two wave vectors. This effect can be used to study spin correlations by means of noise spectroscopy.

Tandem Equipment Arranged Architecture with Exhaust Heat Reuse System for Software-Defined Data Center Infrastructure

In this paper, we propose a novel energy-efficient architecture for software-defined data center infrastructures. In our proposed data center architecture, we include an exhaust heat reuse system that utilizes high-temperature exhaust heat from servers in conditioning humidity and air temperature of office space near the data center. To obtain high-temperature exhaust heat, equipment such as server racks and air conditioners are deployed in tandem so that the aisles are divided into three types: cold, hot, and super-hot. In this paper, to investigate the fundamental characteristics of our proposed data center architecture, we consider various types of data center models and conduct numerical simulations that use results obtained by experiments at an actual data center. Through simulation, we show that the total power consumption by a data center with our proposed architecture is 27 percent lower than that by data center with a conventional architecture. In addition, it is also shown that the proposed tandem equipment arrangement is suitable for obtaining high-temperature exhaust heat and decreasing the total power consumption significantly under a wider range of conditions than in the conventional equipment arrangement.

Efficient oriented particle arrangements for position-based dynamics simulation

We propose two methods to improve the arrangement of oriented particles for position-based dynamics simulation. The first method, within object particle arrangement, segments a target mesh and places a single ellipsoidal particle in each segment. Because the number of oriented particles for simulation is smaller than the number used in a conventional arrangement method which randomly places spherical particles on the target mesh’s surface, we can calculate simulation results more quickly. The second method, on surface particle arrangement, which arranges ellipsoidal particles on the surface of the target mesh, behaves similarly to the conventional method. However, we improve the conventional method by optimizing the position and radiuses of the particles to solve the problem of the protrusion of particles from the mesh surface, which produces inaccurate collision handling results. Based on the results of various experiments, we show that simulations using the oriented particle structures constructed by the proposed methods are more efficient and accurate than those conducted using the conventional method. In addition, we compare the soft body simulation characteristics that appear based on the two proposed methods.

Process simulation for the recovery of lactic acid using thermally coupled distillation columns to mitigate the remixing effect

The objective of this study was to find process simulations of the plant-wide scale lactic acid recovery process using thermally coupled distillation columns to mitigate the remixing effect. The remixing effect has been widely discussed because in a conventional column arrangement it induces a need for a significant amount of energy for repurification in lactic acid recovery processes. One way to overcome high energy consumption is by using thermally coupled distillation columns. This paper suggests and compares two types of thermally coupled distillation columns applied to the plant-wide scale lactic acid recovery process for removing the remixing effect considering a heavy organic impurity and lactic acid oligomerization in the process. The equilibrium stage model based on the RADFRAC module of Aspen Plus was employed for simulating the thermally coupled distillation columns. Simulation results showed that thermally coupled distillation columns can eliminate the remixing effect and reduce energy consumption compared to conventional lactic acid recovery processes.

A needle probe to detect surface enhanced Raman scattering (SERS) within solid specimen.

A needle probe has been developed to obtain surface enhanced Raman scattering data from within a solid specimen located remotely from the spectrometer. It produces the high signal strength of a single mode optical fiber but with a negligible fiber induced background. The observed Raman signal strength is comparable to that obtained with a microscope objective of the same numerical aperture in a conventional spectrometer arrangement and many times larger than that of probes using two fibers.

Optimizing Acquisition Geometry in Shallow Gas Cloud Using Particle Swarm Optimization Approach

Many hydrocarbon explorations in mature fields have been severely affected by complex and overburdening issues, such as shallow gas accumulation, gas pockets, and gas seepage. In this work, a new forward modelling technique is proposed in evaluating the potential survey design for fields affected by shallow gas cloud. In recent years, the implementation of innovative acquisition layouts has been producing significantly better seismic images, especially in the low illumination subsurface area. However, the uncertainty of the effectiveness in new acquisition design subsurface coverage always become a major stumbling block. To overcome this constraint, an optimization approach is suggested through the smart source and receiver location arrangement on the surface, with significant alignment to the conventional source and receiver arrangement approach. The particle swarm optimization (PSO) method is used to find the source-receiver configuration with maximum subsurface illumination coverage for the gas affected field situated in Malaysia Basin. Implementation of the PSO algorithm requires both a velocity model building process and wave field extrapolation from a target reflector to the surface level. The wave field data then was used to simulate receiver optimization outputs which eventually determined the subsurface illumination coverage. The results from the new optimization method for both synthetic model and Malaysia Basin data, offer a greater understanding of the consequences of obstacles caused by shallow anomalies with respect to seismic acquisition, data processing, and interpretation.

Deterministic Pilot Design for Sparse Channel Estimation in MISO/Multi-User OFDM Systems

We study the pilot design problem for sparse channel estimation in OFDM systems where multiple channels are estimated at a single antenna receiver. Such design is applicable to downlink of massive-MIMO systems and also to scenarios where multiple users transmit to a base station at the same carrier frequency. In our design, we deviate from the conventional orthogonal pilot arrangements by assigning the same pilot subcarriers to all transmitters. In the proposed setting, the achieved improvement in spectral efficiency (by reducing pilot overhead) may come at the expense of a more challenging channel estimation block at the receiver. To address this challenge and distinguish between different signals that are arriving at the receiver at the same subcarrier, we propose to select pilot subcarriers through minimizing the coherence of the associated Fourier submatrix, as well as properly assigning different pilot values (complex numbers) to each individual transmitter. We demonstrate that if the channels are sparse enough in time domain, there are simple sparse recovery techniques to simultaneously estimate all the channels, although all transmitters share the same pilot subcarriers. Simulation results demonstrate that the proposed design outperforms existing methods in terms of both mean-square channel estimation error and bit error rate.

A BHJ-thin-film/liquid-electrolyte based electrochemical-sensor for visible light-detection

This study presents a novel photo-sensor configuration that incorporates a layer of liquid electrolyte into the conventional BHJ photodiode arrangement.

Enhanced sensitivity and metabolite coverage with remote laser ablation electrospray ionization-mass spectrometry aided by coaxial plume and gas dynamics.

Laser ablation electrospray ionization-mass spectrometry (LAESI-MS) allows for direct analysis of biological tissues at atmospheric pressure with minimal to no sample preparation. In LAESI, a mid-IR laser beam (λ = 2.94 μm) is focused onto the sample to produce an ablation plume that is intercepted and ionized by an electrospray at the inlet of the mass spectrometer. In the remote LAESI platform, the ablation process is removed from the mass spectrometer inlet and takes place in an ablation chamber, allowing for incorporation of additional optics for microscopic imaging and targeting of specific features of the sample for laser ablation sampling. The ablated material is transported by a carrier gas through a length of tubing, delivering it to the MS inlet where it is intercepted and ionized by an electrospray. Previous proof-of-principle studies used a prolate spheroid ablation chamber with the carrier gas flow perpendicular to the ablation plume. This design resulted in significant losses of MS signal in comparison to conventional LAESI. Here we present a newly designed conical inner volume ablation chamber that radially confines the ablation plume produced in transmission geometry. The carrier gas flow and the expanding ablation plume are aligned in a coaxial configuration to improve the transfer of ablated particles. This new design not only recovered the losses observed with the prolate spheroid chamber design, but was found to provide an ∼12-15% increase in the number of metabolite peaks detected from plant leaves and tissue sections relative to conventional LAESI.

Arrangement of control points for sound spot generation in the multi-point control method

In this research, we considered control point arrangement by using small-scale linear loudspeaker array. The multi-point control method is proposed for sound reproduction in a limited area/direction. This method is based on boundary surface control principle. The desired signal is reproduced in the target point by the sound pressure control in the control points. According to the MINT (multiple-input/output theorem), the signal is reproduced with accuracy in the target point if the number of sound sources more than the number of control points exists. However, a lot of speakers make it difficult to use in real environment. Therefore, small-scale loudspeaker array is preferable. If the number of control points is greater than the number of sound sources, the filter coefficient is approximated by the least squares-method. This approximation affects the sound pressure suppression and sound quality depending on the arrangement of control point. We examined the number of control points arranged. The input signal is the speech signal that has 300-3400 Hz frequency band. We evaluated some arrangement pattern by sound pressure, SD (Spectral Distortion), and PESQ (Perceptual Evaluation of Speech Quality). As a result, good results were obtained than conventional arrangement.