Symmetric Design Research Articles

In Situ Characterization of Kinetics, Mass Transfer, and Active Electrode Surface Area for Vanadium Redox Flow Batteries

Engineering the electrochemical reactor of a vanadium redox flow battery (VRFB) is critical to deliver sufficiently high power densities to achieve cost-effective, grid-scale energy storage. Understanding and ultimately alleviating the cell-level resistive losses in VRFBs fundamentally depend on the ability to accurately measure the electron and mass transfer rates as a function of applied potential and interpret the results in the context of VRFB operation. In this study, an in situ electroanalytical technique of electrochemical reaction in porous electrodes is proposed by a symmetrical cell design for VRFB. For both V2+/V3+ and VO2+/VO2 + redox couples, the polarization curves at different flow rates are acquired on the symmetrical flow cell. The high-frequency resistance is also obtained by electrochemical impedance spectroscopy at open circuit. The ohmic, kinetic, and mass transfer resistance are obtained by deconvoluting the total polarization curve. Corresponding key parameters (i.e., membrane conductivity, reaction rates, and mass transfer coefficients) are obtained along with the specific surface area of porous electrode. The full-cell simulations using extracted key parameters are in excellent agreement with experimental full-cell tests at different applied currents. This novel in situ electroanalytical technique provides an invaluable approach to characterize the performance of electrolyte and electrode in redox flow batteries.

A microfluidic platform for detection and quantification of two biomarkers for rheumatoid arthritis

Early detection of rheumatoid factors (RF) and cyclic citrullinated peptide antibodies (anti-CCP) has been proven to be effective in diagnosing, and even preventing progression to more advanced-stages, of rheumatoid arthritis (RA), thereby decreasing irreversible damage to joints. Herein a novel, dual-target detection approach was integrated in a 45 mm × 62 mm microfluidic chip that featured a symmetrical design in which magnetic beads surface-coated with fragment-crystallizable regions of immunoglobulin G and biotinylated CCP enabled detection of these two RA biomarkers within 55 min with only 5 μL of serum. This device could therefore be useful for rapid clinical diagnosis of this all-too-common ailment.

Almost simple groups as flag-transitive automorphism groups of symmetric designs with λ prime

In this article, we study symmetric designs with λ prime admitting a flag-transitive and point-primitive automorphism groups G of almost simple type. We prove that either D is one of the six well-known examples of biplanes and triplanes, or D is the point- hyperplane design of PG(n−1,q) with λ = (q^{n−2}−1)/(q−1) prime and X = PSLn(q).

Analisa Pengaruh Desain 6 Fasa dengan Sistem 1 Lapis dan 3 Medan Fluks pada Motor Induksi 3 Fasa Terhadap Torsi dan Kecepatan Motor

This study aims to examine the effect of a 6-phase design on the torque and speed of a 3-phase induction motor with a symmetrical single-layer design system. The research was conducted in the Power Systems Laboratory of Electrical Engineering, Padang Institute of Technology by continuing to operate a 3-phase induction motor with this 6-phase design in this 3-phase electric power system. Then it is compared with the performance of a conventional 3-phase induction motor and focuses on the torque and speed of the motor. The induction motors that are the object of research are 3-phase induction motors, 0.75 KW, 1 HP, 380 V/Y, 1.3A, 50 HZ, and 2880 RPM. The results of the study indicate that there is a decrease in torque in the 1-layer symmetrical 6-phase design motor with 3 flux fields due to a decrease in the ability of the motor with increasing speed. This is due to the occurrence of a flux field attached to one of the two coils which is serialized to the other 2 coils with different types of magnetic poles so that they weaken each other which affects the decrease in the ability to drive the motor so that the torque prod. used decreases

Numerical and experimental investigation of gas flow field variations in three-dimensional printed gas-dynamic virtual nozzles

Gas-dynamic virtual nozzles (GDVNs) play a vital role in delivering biomolecular samples during diffraction measurements at X-ray free-electron laser facilities. Recently, submicrometer resolution capabilities of two-photon polymerization 3D printing techniques opened the possibility to quickly fabricate gas-dynamic virtual nozzles with practically any geometry. In our previous work, we exploited this capability to print asymmetric gas-dynamic virtual nozzles that outperformed conventional symmetric designs, which naturally leads to the question of how to identify the optimal gas-dynamic virtual nozzle geometry. In this work, we develop a 3D computational fluid dynamics pipeline to investigate how the characteristics of microjets are affected by gas-dynamic virtual nozzle geometry, which will allow for further geometry optimizations and explorations. We used open-source software (OpenFOAM) and an efficient geometric volume-of-fluid method (isoAdvector) to affordably and accurately predict jet properties for different nozzle geometries. Computational resources were minimized by utilizing adaptive mesh refinement. The numerical simulation results showed acceptable agreement with the experimental data, with a relative error of about 10% for our test cases that compared bell- and cone-shaped sheath-gas cavities. In these test cases, we used a relatively low sheath gas flow rate (6 mg/min), but future work including the implementation of compressible flows will enable the investigation of higher flow rates and the study of asymmetric drip-to-jet transitions.

Symmetric designs with λ ⩽ 10 admitting flag-transitive and point-primitive almost simple automorphism groups

In this article, we study symmetric (v,k,λ) designs D with λ⩽10 admitting flag-transitive and point-primitive almost simple automorphism group G with socle X. We, in particular, determine all such possible designs and show that such a design is isomorphic to a Desarguesian plane with parameter set (q2+q+1,q+1,1) and X=PSL3(q), or D is isomorphic to one of the seventeen well-known designs.

Reduction of Radar Cross Section by Adopting Symmetrical Coding Metamaterial Design for Terahertz Frequency Applications.

This work focused on the novel and compact 1-bit symmetrical coding-based metamaterial for radar cross section reduction in terahertz frequencies. A couple of coding particles were constructed to impersonate the elements '0' and '1', which have phase differences of 180°. All the analytical simulations were performed by adopting Computer Simulation Technology Microwave Studio 2019 software. Moreover, the transmission coefficient of the element '1' was examined as well by adopting similar software and validated by a high-frequency structure simulator. Meanwhile, the frequency range from 0 to 3 THz was set in this work. The phase response properties of each element were examined before constructing various coding metamaterial designs in smaller and bigger lattices. The proposed unit cells exhibit phase responses at 0.84 THz and 1.54 THz, respectively. Meanwhile, the analysis of various coding sequences was carried out and they manifest interesting monostatic and bistatic radar cross section (RCS) reduction performances. The Coding Sequence 2 manifests the best bistatic RCS reduction values in smaller lattices, which reduced from -69.8 dBm2 to -65.5 dBm2 at 1.54 THz. On the other hand, the monostatic RCS values for all lattices have an inclined line until they reach a frequency of 1.0 THz from more than -60 dBm2. However, from the 1.0 THz to 3.0 THz frequency range the RCS values have moderate discrepancies among the horizontal line for each lattice. Furthermore, two parametric studies were performed to examine the RCS reduction behaviour, for instance, multi-layer structures and as well tilt positioning of the proposed coding metamaterial. Overall it indicates that the integration of coding-based metamaterial successfully reduced the RCS values.

Ultra-sensitive one-dimensional phononic crystals temperature sensor: theoretical optimization

Abstract The present study intends to solve the problem of low-temperature sensitivity of most conventional period materials. A solid/solid one-dimensional phononic crystal design is proposed as a pragmatic thermal sensor. Here, each unit cell of the proposed phononic crystal sensor is designed from epoxy and concrete. In this structure, irregularity in layers’ arrangement results in the generation of resonant peaks at the transmission spectrum. The irregularity is introduced to the system by stacking two mirror phononic crystals to form a whole symmetric phononic crystal design. Thermal variations lead to significant changes in Young’s modulus of concrete and epoxy; consequently, transmission spectra and local resonant peaks are shifted as well. Firstly, the band gap changes, and sensor performance were investigated under different conditions such as the incident angle and the number of unit cells to get the optimum parameters. Meanwhile, promising results have been obtained, with increasing the incident angle, the sensitivity increases exponentially till it reaches 1.5 × 103 Hz/°C at an incident angle = 18°. Also, with increasing the temperature from 25 to 100 °C, the sensitivity increases dramatically from 188.8 to 362.4 Hz/°C, respectively. In addition, the largest value of Q-factor was investigated at periodicity number = 4. Moreover, in this regard, the Q-factor has the value of 3708 at 25 °C and it reaches to the value of 896.6 at 100 °C. That is to say, the obtained results may be useful in designing thermal sensors with a high sensitivity value.

Symmetrical Hardware-Software Design for Improving Physical Activity with a Gamified Music Step Sensor Box

Physical inactivity, the fourth leading cause of death worldwide, can harm the economy, national growth, community welfare, health, and quality of life. On the other hand, physical activities (PA) have numerous advantages, including fewer cardiovascular diseases, cancer, and diabetes, fewer psychological disorders, and improved cognitive abilities. Despite the benefits of PA, people are less likely to participate. The main factor is a lack of entertainment in exercise, which demotivates society from engaging in healthy activities. In this work, we proposed a hardware-software symmetry that can entertain people while performing PA. We developed a step-box with sensors and a gamified music application synchronized with the footsteps. The purpose of this study is to show that incorporating appropriate gamification allows participants to engage actively in tedious and economic exercises. Participants (N = 90) participated in 20-min daily exercise sessions for three days. A 5-point Likert scale was used to assess efficiency, effectiveness, and satisfaction following exercise sessions. The results show that the gamified sensor step-box increased efficiency, effectiveness, and participant satisfaction. The findings suggest that gamification fundamentals in simple exercises increase excitement and may help people to maintain PA.

Efficiency of Sum Constructed Automorphic Symmetric Balanced Incomplete Block Designs

Several construction methods have been introduced to build the elements of balanced incomplete block designs (BIBDs) for specific parameters, with different techniques suggested for testing their existence. There is still no general technique to determine the existence of the designs that have been realized. In this study the efficiencies of some given automorphic symmetric balanced incomplete block designs (AUSBIBD) formed by sum construction method have been presented in details alongside existence and non-existence of such designs. The process involved the application of sum construction method to give new designs of parameters D (v, b, λ1+λ2) and an application of Bruck Ryser Chwola theorem extensively. A test design constructed using the described method was found to be existing with an efficiency of 76.38%. Sum constructed designs are more applicable in agricultural fields as witness in case of KEFRI-Kenya.

A novel short fiber Bragg grating accelerometer based on a V-type dual mass block structure for low- and medium-frequency vibration measurements

A novel short fiber Bragg grating (FBG) accelerometer based on a dual mass block structure is presented in this paper. The sensor is established on a solid, symmetrical design comprising a V-type beam. The configuration in the FBG accelerometer causes the FBG fiber to distort twice as much when subjected to external vibration. The theoretical research and optimization of the FBG accelerometer's natural frequency and sensitivity are performed using MATLAB software, while static structural stress and modal simulation analysis are examined using ANSYS software. An experimental test is applied to evaluate the implementation of the sensors. The natural frequency of the sensor is 880 Hz, and its stability frequency response is flat in the 20–340 Hz low- to middle-frequency range. The linearity of the average sensitivity is approximately 66.95 pm/g, and the transverse anti-interference of the FBG fiber is around 6.53%. This work proposes a suitable method to observe low- and medium-frequency vibration signals in large-scale applications.

Enhancing two-photon uncaging sensitivity in symmetrical dimeric conjugated coumarin cages: Role of the coupling core

A series of symmetrical conjugated dimeric coumarinyl cages has been synthesized by grafting 7-diethlyaminocoumarin (DEAC) cages via π-linkers onto different aromatic cores displaying various electronic character (electron-withdrawing: benzobisthiazole BBTz, electron-donating: carbazole or ambivalent: fluorenyl). Due to their symmetrical design, all conjugated dimeric derivatives showed enhanced two-photon absorption at 730 nm, the electron-withdrawing core leading to the highest response (over 3000 GM). All dimeric derivatives retained the uncaging ability of the DEAC cage, with a strong influence of the nature of the core on the uncaging quantum yield. While the fluorenyl core led to an uncaging quantum yield similar to DEAC, the BBTz core led to a twice larger uncaging quantum yield and the carbazole core to even larger uncaging quantum yield (60 %). As a result, both electron-donating and electron-withdrawing cores lead to symmetrical dimeric DEAC derivatives showing unprecedented two-photon uncaging photo-sensitivity (up to 550 GM).

Comparison of tibial implant positioning between symmetrical and anatomical design implants in unicompartmental knee arthroplasty for Japanese patients.

In unicompartmental knee arthroplasty (UKA) procedures, maximizing the bone coverage of the tibial implant and eliminating the medial and posterior overhang would be optimal. We commonly used Physica ZUK® (ZUK), which is a symmetrical design. Alternatively, since Persona Partial Knee® (PPK) was developed in 2017 with an anatomical design to improve bone coverage, we started PPK. We hypothesized that the PPK facilitated better bone coverage than the ZUK without obvious overhangs. This study evaluated the bone coverage and the medial and posterior overhang of these differently designed tibial implants. Seventy-nine knees from 68 patients who underwent UKA were evaluated. Cases were categorized into the ZUK (41 knees) and PPK (38 knees) groups. CT images were acquired before surgery and 1week after surgery. We measured the tibial bone coverage, and the medial and posterior overhang by 3D software. The bone coverages were 103.8 ± 4.8% and 102.0 ± 3.0%, the medial overhangs were 2.2 ± 1.2mm and 1.4 ± 1.1mm, and the posterior overhangs were 0.6 ± 1.3mm and 0.4 ± 1.2mm for the ZUK and PPK groups, respectively. The bone coverage and medial overhang were significantly different between the groups, with ZUK being larger. Patients who received PPK had significantly smaller medial overhangs and better bone coverage. PPK is more likely to give better results than ZUK.

Difference in implant design affects midflexion rotational laxity in cruciate-retaining total knee arthroplasty: a computer navigation study

PurposeThis study aimed to compare midflexion rotational laxity between two different design concept models of cruciate-retaining total knee arthroplasty: symmetrical surface design of neutral joint line obliquity and asymmetrical surface design of varus joint line obliquity.MethodsSixty-three knees that underwent cruciate-retaining total knee arthroplasty were evaluated. Manual maximum passive rotational stress without acceleration was applied to the knees under navigation monitoring. Pre-operative and post-operative internal and external rotational angles were measured at 30°, 45°, 60°, and 90° knee flexion.ResultsThe post-operative internal rotational laxity was significantly increased compared with pre-operative levels at 30°, 45°, 60°, and 90° flexion among all subjects (mean 9.7° vs 11.1°, 10.6° vs 11.6°, 11.2° vs 12.9°, and 13.2° vs 14.9°; p = 0.01, 0.04, 0.001, and 0.008, respectively). The post-operative external rotational laxity was significantly decreased compared to pre-operative levels at 30°, 45°, 60°, and 90° flexion among all subjects (mean 10.8° vs 6.8°, 12.5° vs 9.4°, 12.8° vs 10.0°, and 11.3° vs 9.5°; p < 0.0001, < 0.0001, < 0.0001, and 0.0008, respectively). The post-operative total rotational laxity significantly decreased, compared with pre-operative levels, at 30° and 45° flexion among all subjects (mean 20.4° vs 17.9°, and 23.1° vs 21.1°; p = 0.002 and 0.04, respectively). The post-operative total rotational laxity was significantly smaller in asymmetrically designed total knee arthroplasty than in symmetrically designed total knee arthroplasty at 30°, 45°, and 60° flexion (mean 19.3° vs 15.8°, 22.8° vs 18.7°, and 24.4° vs 20.8°; p = 0.03, 0.03, and 0.02, respectively), whereas no significant difference was observed at 90° flexion.ConclusionCompared to symmetrical surface design, asymmetrical surface design resulted in lower rotational laxity at the midflexion range in cruciate-retaining total knee arthroplasty.Level of evidenceIII.

On a characterization of symmetric balanced incomplete block designs

On a characterization of symmetric balanced incomplete block designs

SetRkNN: Efficient and Privacy-Preserving Set Reverse kNN Query in Cloud

The advance of cloud computing has driven a new paradigm of outsourcing large-scale data and data-driven services to public clouds. Due to the increased awareness of privacy protection, many studies have focused on addressing security and privacy issues in outsourced query services. Although many privacy-preserving schemes have been proposed for various query types, the set reverse k nearest neighbors (RkNN) query is still an unexplored area. Even if some existing schemes can be adapted to achieve privacy-preserving set RkNN queries, they will suffer from linear search efficiency. As a steppingstone, in this paper, we propose an efficient and privacy-preserving set RkNN query scheme over encrypted data with sublinear query efficiency. Specifically, we first design an inverted prefix index to organize the set dataset and propose an algorithm to traverse the index with sublinear search efficiency. Then, we propose two oblivious data comparison protocols based on a symmetric homomorphic encryption (SHE) scheme and design the private filter/refinement protocols to preserve the privacy of index searching. After that, we propose an access pattern privacy-preserving set RkNN query scheme by using private filter/refinement protocols. Rigorous security analysis demonstrates that our scheme can protect data privacy and access pattern privacy. Experimental results indicate that our scheme is more efficient than the available naive solution in terms of computational costs and communication overheads.

Local resolution of currents through electrical joints consisting of materials with different conductivity

Within this work the impact of contact materials with higher volume resistivity as leaded solder are investigated in terms of comparability of the current conduction through the joint. An approach was developed to experimentally determine the qualitative local current density by magnetic field imaging (MFI) at ribbon-to-ribbon contact samples. The result reveals that the MFI technique on a symmetric sample design allows the evaluation of the current paths in two-dimensional contact areas. Different resistivities of the contact material result in characteristic differences in current distribution through the joint. Low resistive Sn60Pb40-soldererd contacts exhibit localized current injection whereas the tested contact based on electrically conductive adhesives (ECAs) show an extended current flow through the ECA-based contact. A FEM-based simulation model to mimic the used setup was developed and confirmed the results by taking different contact material resistivities into account. For materials with resistivities larger than 1 · 10−3 Ω · cm current injection was found to spread-spatially within the tested contact geometry. Contact material development as well as contact design can benefit from that approach, allowing consumption and material composition optimization. A further advantage is the feasibility of the method to study production failures like inhomogeneous ECA distribution enabling a non-destructive monitoring of process stability and root cause analysis.

Construction of Non-Symmetric Balanced Incomplete Block Design through Combination of Symmetric Disjoint Balanced Incomplete Block Designs

Construction of Non-Symmetric Balanced Incomplete Block Design through Combination of Symmetric Disjoint Balanced Incomplete Block Designs

Dynamically changeable terahertz metamaterial absorbers with intelligent switch and high sensitivity and wide and narrow band perfect absorption.

In this work, we theoretically designed a dynamically changeable terahertz metamaterial absorber with intelligent switch and high sensitivity, wide band and narrow band perfect absorption based on the combination of Dirac semimetal (BDS) and vanadium dioxide (VO2). It features two methods for absorption adjustment: altering the Fermi energy level of BDS to modify the resonant frequency of the absorption peaks and utilizing the phase change of VO2 to regulate the absorption rate of the peaks. In addition, its rotational symmetric design ensures strong polarization-insensitivity. The simulation results demonstrate the presence of two narrowband absorption peaks and one mini-broadband absorption peak within the frequency range of 6.0-9.5 THz, all with absorption rates exceeding 90%. We provide an explanation of the absorption mechanism of the device, employing the relative impedance theory and localized surface plasmon resonance to analyze its electric field distribution. We also defined the refractive index sensitivity (S), which is SI = 378 GHz per RIU and SIII = 204 GHz per RIU. Our device possesses high sensitivity and two methods of adjusting absorption modes, which endow it with advantages in the fields of metamaterial absorbers, intelligent switch, and optical sensors.

Stress-strain magnetoactive propulsion system

It is possible to create deformations in magnetically active polymeric materials by applying magnetic fields to them. This work develops a symmetrical design scheme of the device, in which the drive and control are carried out by two actuators located on opposite sides. The symmetric scheme with control from two sides allows transporting objects (cargo) in mutually opposite directions (forward and backward). It is proposed to use a magnetically active gel together with a magnetically active elastomer as magnetically active materials. The resulting force effect in the device actuator is produced by interaction of magnetic fields of electromagnets with magnetic fields of permanent magnets. Expressions for obtaining alternating magnetic fields which create conditions for generating alternating magnetic forces in the actuator of the device are given. A prototype design with a controller control device in which signals are generated for an optimum current pulse generator with adjustable duty cycle and duration is presented.