A NEW ARRAY STRUCTURE FOR ESTIMATING 2-D DIRECTION-OF-ARRIVAL:Y-SHAPED ARRAY

This paper presents a new array structure for estimating two-dimensional (2-D) direction-of-arrivals (DOAs). The structure is called Y-shaped array, which has 10% better accuracy potential than the newly-developed L-shaped array. A great merit is its ability to estimate 2-D DOAs whichever directions the arriving signals come from, compared with L-shaped array whose performance depends on DOAs. Simulation results are given to demonstrate the performance of the new array.

Expansion of a Y-Shaped Antenna Array and Optimization of the Future Antenna Array in Malaysia for Astronomical Applications

To achieve high quality images from the sky by extending an existing interferometric array, in this work, the Geometrical Method (GM), Genetic Algorithm (GA), and Division Algorithm (DA) are compared. These methods are each applied independently to an interferometer array starting from the same initial conditions. Using the GM method, the spiral configuration is suggested as an optimum arrangement that provides the desired u-v coverage with low side lobe levels (SLLs). Using the GA method, as the number of generations is increased, the unsampled cells are reduced, enhancing the imaging quality. As such, the algorithm improves the overlapped samples as it works with a greater number of generations. Moreover, the GA is able to suppress the SLL. Finally, the DA is applied to such an array. Results show that the DA is able to process the sampled data with less overlapping of the data in the snapshot observations, in comparison to the other discussed configurations in this paper;effectively the DA reduces the overlapped samples, such that it is more efficient than the GA. The configuration of antennas that arrives by applying the DA method can achieve a certain image quality with less overlapping, as compared to the configuration arriving by applying the GA method. The calculated SLLs for the DA configuration are used to demonstrate that the efficiency of the DA is potentially better than that of the GA. Moreover, the GA and DA algorithms discussed in this study are applied to an array of 10 antennas with coordinates that represent the antennas deployed in Malaysia. Results show that the DA can reduce the overlapping of the samples more efficiently than the GA for a 6-hour tracking observation and in terms of unsampled cells the DA has the same efficiency of the GA.

Gastrotracheal fistula:Treatment with a covered self-expanding Y-shaped metallic stent

A 67-year-old man had a sev-ere cough and pulmonary infection for 1 wk before seeking evaluation at our hospital.He had undergone esophagectomy with gastric pull-up and radiotherapy for esophageal cancer 3 years previously.After admission to our hospital,gastroscopy and bronchoscopy revealed a fistulous communication between the posterior tracheal wallnear the carina and the upper residual stomach.We measured the diameter of the trachea and bronchus and determined the site and size of the fistula using multislice computed tomography and gastroscopy.A covered self-expanding Y-shaped metallic stent was implanted into the trachea and bronchus.Subsequently,the fistula was closed completely.The patient tolerated the stent well and had good palliation of his symptoms.

Y-shaped block copolymers of poly(ethylene glycol) and poly(N-isopropylacrylamide) synthesized by ATRP

Novel Y-shaped block copolymers of poly（ethylene glycol） and poly（N-isopropylacrylamide）, PEG-b-（PNIPAM）2, were successfully synthesized through atom transfer radical polymerization （ATRP）. A difunctional macroinitiator was prepared by esterification of 2,2-dichloroacetyl chloride with poly（ethylene glycol） monomethyl ether （PEG）. The copolymers were obtained via the ATRP ofN-isopropylacrylamide （NIPAM） at 30℃ with CuCl/Me6TREN as a catalyst system and DMF/H2O （v/v = 3：1） mixture as solvent. The resulting copolymers were characterized by gel permeation chromatography （GPC） and ^1H NMR. These block copolymers show controllable molecular weights and narrow molecular weight distributions （PDI 〈 1.15）. Their phase transition temperatures and the corresponding enthalpy changes in aqueous solution were measured by differential scanning calorimetry （DSC）. As a result, the phase transition temperature of PEG45-b-（PNIPAM55）2 is higher than that of PNIPAM, however, the corresponding enthalpy change is much lower, indicating the significant influence of the macromolecular composition and architecture on the phase transition.

基于Y-shaped路网的早高峰拼车定价策略

针对交通资源配置有限导致的早高峰通勤拥堵问题,借鉴共享经济理论,引入拼车出行概念,充分考虑通勤者出行方式和Y-shaped路网特点,建立了基于通勤者出行效益的拼车定价模型.模型结合费用补偿机制,讨论了以平台利润最大化和系统负效用最小化为目标的拼车定价策略,并给出了定价策略有效的阈值条件.研究结果表明,当通勤者都参与到拼车服务中时,拼车平台利润和交通系统负效用在其相应拼车定价策略下均能达到最优值,并且以交通系统负效用最小化为目标的拼车定价策略能消除Y-shaped路网中瓶颈处的交通拥堵.

Deformation and defects in hydroforming of Y-shaped tubes

Hydroforming process of a Y-shaped stainless steel tube was investigated through numerical simulation and experiments. The forming process and reasons of typical defects were analyzed with three different loading paths. Thickness distribution of formed Y-shaped tube was obtained. It is shown by numerical and experimental results that the transition regions are depressed in the forming condition of low inner pressure and wrinkles occur, while fracture occurs in the forming condition of high inner pressure. After forming, the thickness in left transition fillet region is the largest, that in fight transition fillet region is thinner, and the thinnest thickness is at the top of the protrusion. The original thickness line is below the top of the protrusion. The thinning area occurs above this line, while the thickening area is below this line. The maximum thinning rate is significantly increased as the calibration pressure increases, while the maximum thickening rate remains almost unchanged.

Binary collision approximation for solitary waves in a Y-shaped granular chain

We implement a binary collision approximation to study solitary wave propagation in a two-dimensional double Y- shaped granular chain. The solitary wave was transmitted and reflected when it met the interface of the bifurcated branches of the Y-shaped granular chains. We obtain the analytic results of the ratios of the transmitted and reflected speeds to the incident speed of the solitary wave, the maximum force between the two neighbor beads in a solitary wave, and the total time taken by the pulse to pass through each branch. All of the analytic results are in good agreement with the experimental observations from Daraio et al. [Phys. Rev. E 82 036603 （2010）]. Moreover, we also discuss the delay effects on the arrival of split pulses, and predict the recombination of the split waves traveling in branches in the final stem of asymmetric systems. The prediction of pulse recombination is verified by our numerical results.

Evaluation of ultimate bearing capacity of Y-shaped vibro-pile

Based on Mindlin stress solution, a numerical computational method was proposed to calculate the stresses in the ground induced by side friction and the resistance of Y-shaped vibro-pile. The improved Terzaghi's and ЪерезанцевВГ's methods for ultimate bearing capacity evaluation were proposed by considering the stress strength induced by friction resistance at pile head level of Y-pile. A new method to calculate the ultimate bearing capacity of Y-pile was also proposed based on the assumptions of soil failure mode at the tip of Y-pile and the use of Mohr-Coulomb soil yield criterion and Vesic compressive correction coefficient with the induced stresses in the ground. Based on the comparisons with the field static load test results, it is found that the improved Terzaghi's method gives higher ultimate capacity, while the other two methods shows good agreement with the field results.

Recent Advances in In-Memory Computing:Exploring Memristor and Memtransistor Arrays with 2D Materials

The conventional computing architecture faces substantial chal-lenges,including high latency and energy consumption between memory and processing units.In response,in-memory computing has emerged as a promising alternative architecture,enabling computing operations within memory arrays to overcome these limitations.Memristive devices have gained significant attention as key components for in-memory computing due to their high-density arrays,rapid response times,and ability to emulate biological synapses.Among these devices,two-dimensional(2D)material-based memristor and memtransistor arrays have emerged as particularly promising candidates for next-generation in-memory computing,thanks to their exceptional performance driven by the unique properties of 2D materials,such as layered structures,mechanical flexibility,and the capability to form heterojunctions.This review delves into the state-of-the-art research on 2D material-based memristive arrays,encompassing critical aspects such as material selection,device perfor-mance metrics,array structures,and potential applications.Furthermore,it provides a comprehensive overview of the current challenges and limitations associated with these arrays,along with potential solutions.The primary objective of this review is to serve as a significant milestone in realizing next-generation in-memory computing utilizing 2D materials and bridge the gap from single-device characterization to array-level and system-level implementations of neuromorphic computing,leveraging the potential of 2D material-based memristive devices.

Transfer characteristics of dynamic biochemical signals in non-reversing pulsatile flows in a shallow Y-shaped microfluidic channel: signal filtering and nonlinear amplitude-frequency modulation

The transports of the dynamic biochemical signals in the non-reversing pulsatile flows in the mixing microchannel of a Y-shaped microfluidic device are ana- lyzed. The results show that the mixing micro-channel acts as a low-pass filter, and the biochemical signals are nonlinearly modulated by the pulsatile flows, which depend on the biochemical signal frequency, the flow signal frequency, and the biochemical signal transporting distance. It is concluded that, the transfer characteristics of the dynamic biochemical signals, which are transported in the time-varying flows, should be carefully considered for better loading biochemical signals on the cells cultured on the bottom of the microfluidic channel.

Low profile cavity-embedded ultra-wideband UHF array antenna with end-fire beams

A low-profile,vertically polarized,ultra-wideband array antenna with end-fire beams operating in an ultra-high frequency(UHF)band is developed in this paper.The array antenna consists of 1×16 log-periodic top-hat loaded monopole antenna arrays and is feasible to embed into a shallow cavity to further reduce the array height.Capacitance is introduced in the proposed antenna element to reduce profile height and the rectangular top hats are carefully designed to minimize the transverse dimension.Simulated results show that when the antenna array operates in a frequency range of 300 MHz-900 MHz,the end-fire radiation pattern achieves±45°scanning range in the horizontal plane.Then prototypes of the proposed end-fire antenna element and a uniformly spaced linear array(1×2)are fabricated and validated.The end-fire antenna array should be suitable for airborne applications where low-profile and conformal scanning phased antenna arrays with end-fire radiations are required.This design is attractive for airborne platform applications that are used to search,discover,identify,and scout the aerial target with vertically polarized beams.

Y-Shaped Intra-Scleral Fixated Lens versus Retro-Pupillary Iris Claw Lens in the Treatment of Aphakia

Background: Many reasons can lead to an aphakia without adequate capsular support for implantation of a posterior chamber intraocular lens (IOL), such as intraoperative unintentional rupture of posterior capsule during phacoemulsification, planned intracapsular cataract extraction, ocular trauma and lens dislocation due to congenital and acquired causes. Purpose: To compare Y-shaped intra-scleral fixation of a posterior chamber IOL with retro pupillary fixation of an iris-claw intraocular lens (IOL) for Aphakic eyes without sufficient capsular support as respects safety, visual recovery and complications of both methods. Patients and Methods: One hundred Aphakic eyes were arbitrarily distributed between two groups. Group A included 50 eyes treated with retropupillary fixation of iris claw lens and group B included 50 eyes treated with Y-shaped intra-scleral fixation technique. Preoperative, intraoperative and postoperative data were analysed including best corrected visual acuity (BCVA), intraocular pressure (IOP), surgical time, intraoperative problems, IOL malposition and postoperative complications. Following up on patients was carried out for at least six months. Results: The mean duration of surgery was 21 ± 5.3 min in group A and was 53.4 ± 6.9 min in group B (p-value 0.05). IOL tilt was found in 0 (0%) eyes in group A and in 5 (10%) eyes in group B (p 0.05). Conclusion: The results of our study indicated that both methods are satisfactory in correcting aphakia without sufficient capsular support as regards postoperative best corrected visual acuity (BCVA);however the surgical technique of retropupillary iris claw lens is easier, shorter, with low intra- and postoperative complications and safer than those used for intra-scleral fixation of IOL. But for eyes which lack both iris and capsular support, a scleral fixation of a posterior chamber IOL remains the only option.

Customization of FeNi alloy nanosheet arrays inserted with biomass-derived carbon templates for boosted electromagnetic wave absorption

Electromagnetic wave(EMW)-absorbing materials have considerable capacity in the military field and the prevention of EMW radiation from harming human health.However,obtaining lightweight,high-performance,and broadband EMW-absorbing material remains an overwhelming challenge.Creating dielectric/magnetic composites with customized structures is a strategy with great promise for the development of high-performance EMW-absorbing materials.Using layered double hydroxides as the precursors of bimetallic alloys and combining them with porous biomass-derived carbon materials is a potential way for constructing multi-interface heterostructures as efficient EMW-absorbing materials because they have synergistic losses,low costs,abundant resources,and light weights.Here,FeNi alloy nanosheet array/Lycopodium spore-derived carbon(FeNi/LSC)was prepared through a simple hydrothermal and carbonization method.FeNi/LSC presents ideal EMW-absorbing performance by benefiting from the FeNi alloy nanosheet array,sponge-like structure,capability for impedance matching,and improved dielectric/magnetic losses.As expected,FeNi/LSC exhibited the minimum reflection loss of-58.3 dB at 1.5 mm with 20wt%filler content and a widely effective absorption bandwidth of 4.92 GHz.FeNi/LSC composites with effective EMW-absorbing performance provide new insights into the customization of biomass-derived composites as high-performance and lightweight broadband EMW-absorbing materials.

Comparison of lag screws and double Y-shaped miniplates in the fixation of anterior mandibular fractures

BACKGROUNDMandibular fractures constitute about 80.79% of maxillofacial injuries inAlexandria University, either as isolated mandibular fractures or as a part ofpanfacial fractures. The combination of symphyseal and parasymphyseal fracturesrepresent 47.09% of the total mandibular fractures.AIMTo compare the effectiveness of lag screws vs double Y-shaped miniplates in thefixation of anterior mandibular fractures.METHODSThis study is a prospective randomized controlled clinical trial, performed onsixteen patients with anterior mandibular fractures. Patients were divided equallyinto two groups, each consisting of eight patients. Group 1: Underwent openreduction and internal fixation using two lag screws. Group 2: Underwent openreduction and internal fixation using double Y-shaped plates. The followingparameters were assessed: operating time in minutes, pain using a visual analogscale, edema, surgical wound healing for signs and symptoms of infection,occlusion status and stability, maximal mouth opening, and sensory nervefunction. Cone beam computed tomography was performed at 3 and 6 mo tomeasure bone density and assess the progression of fracture healing.RESULTSThe study included 13 males (81.3%) and 3 females (18.8%) aged 26 to 45 years(mean age was 35.69 ± 6.01 years). The cause of trauma was road traffic accidentsin 10 patients (62.5%), interpersonal violence in 3 patients (18.8%) and othercauses in 3 patients (18.8%). The fractures comprised 10 parasymphyseal fractures(62.5%) and 6 symphyseal fractures (37.5%). The values of all parameters were comparable in both groups with no statistically significant difference except forthe mean bone density at 3 mo postoperatively which was 946.38 ± 66.29 in group 1 and 830.36 ± 95.53 in group 2 (P = 0.015).CONCLUSIONBoth lag screws and double Y-shaped miniplates provide favorable means offixation for mandibular fractures in the anterior region. Fractures fixed with lagscrews show greater mean bone density at 3 mo post-operation, indicative ofhigher primary stability and faster early bone healing. Further studies with largersample sizes are required to verify these conclusions.

Application and prospect of the fluid cooling system of solar arrays for probing the Sun

The Solar Close Observations and Proximity Experiments(SCOPE)mission,which has been proposed by the Yunnan Observatories,Chinese Academy of Sciences,aiming to operate at a distance of 5 to 10 solar radii from the Sun,plans to complete the in situ detection of the solar eruption process and observation of the magnetic field structure response.The solar flux received by the satellite ranges from 10^(3) to 10^(6) Wm^(-2),which poses challenges for thermal management of the solar arrays.In this work,the solar array cooling system of the Parker Solar Probe is discussed,the developments of the fluid loop technique are reviewed,and a research plan for a next-generation solar array cooling system is proposed.This paper provides a valuable reference for novel thermal control systems in spacecraft for solar observation.

Sparse antenna array design methodologies:A review

Designing a sparse array with reduced transmit/receive modules(TRMs)is vital for some applications where the antenna system’s size,weight,allowed operating space,and cost are limited.Sparse arrays exhibit distinct architectures,roughly classified into three categories:Thinned arrays,nonuniformly spaced arrays,and clustered arrays.While numerous advanced synthesis methods have been presented for the three types of sparse arrays in recent years,a comprehensive review of the latest development in sparse array synthesis is lacking.This work aims to fill this gap by thoroughly summarizing these techniques.The study includes synthesis examples to facilitate a comparative analysis of different techniques in terms of both accuracy and efficiency.Thus,this review is intended to assist researchers and engineers in related fields,offering a clear understanding of the development and distinctions among sparse array synthesis techniques.

Low-Complexity Reconstruction of Covariance Matrix in Hybrid Uniform Circular Array

Spatial covariance matrix(SCM) is essential in many multi-antenna systems such as massive multiple-input multiple-output(MIMO). For multi-antenna systems operating at millimeter-wave bands, hybrid analog-digital structure has been widely adopted to reduce the cost of radio frequency chains.In this situation, signals received at the antennas are unavailable to the digital receiver, and as a consequence, traditional sample average approach cannot be used for SCM reconstruction in hybrid multi-antenna systems. To address this issue, beam sweeping algorithm(BSA) which can reconstruct the SCM effectively for a hybrid uniform linear array, has been proposed in our previous works. However, direct extension of BSA to a hybrid uniform circular array(UCA)will result in a huge computational burden. To this end, a low-complexity approach is proposed in this paper. By exploiting the symmetry features of SCM for the UCA, the number of unknowns can be reduced significantly and thus the complexity of reconstruction can be saved accordingly. Furthermore, an insightful analysis is also presented in this paper, showing that the reduction of the number of unknowns can also improve the accuracy of the reconstructed SCM. Simulation results are also shown to demonstrate the proposed approach.

Simulation and fabrication of in vitro microfluidic microelectrode array chip for patterned culture and electrophysiological detection of neurons

To enable the detection and modulation of modularized neural networks in vitro,this study proposes a microfluidic microelectrode array chip for the cultivation,compartmentalization,and control of neural cells.The chip was designed based on the specific structure of neurons and the requirements for detection and modulation.Finite-element analysis of the chip’s flow field was conducted using the COMSOL Multiphysics software,and the simulation results show that the liquid within the chip can flow smoothly,ensuring stable flow fields that facilitate the uniform growth of neurons within the microfluidic channels.By employing MEMS technology in combination with nanomaterial modification techniques,the microfluidic microelectrode array chip was fabricated successfully.Primary hippocampal neurons were cultured on the chip,forming a well-defined neural network.Spontaneous electrical activity of the detected neurons was recorded,exhibiting a 23.7%increase in amplitude compared to neuronal discharges detected on an open-field microelectrode array.This study provides a platform for the precise detection and modulation of patterned neuronal growth in vitro,potentially serving as a novel tool in neuroscience research.

Development of an enhanced online tritium monitoring system using plastic scintillation fiber array

Tritium,a radioactive nuclide discharged by nuclear power plants,poses challenges for removal.Continuous online monitoring of tritium in water is crucial for real-time radiation data,given its predominant existence in the environment as water.This paper presents the design,simulation,and development of a tritium monitoring device utilizing a plastic scintillation fiber(PSF)array.Experimental validation confirmed the device’s detection efficiency and minimum detectable activity.The recorded detection efficiency of the device is 1.6×10^(-3),which exceeds the theoretically simulated value of 4×10^(-4)by four times.Without shielding,the device can achieve a minimum detectable activity of 3165 Bq L^(-1)over a 1600-second measurement duration.According to simulation and experimental results,enhancing detection efficiency is possible by increasing the number and length of PSFs and implementing rigorous shielding measures.Additionally,reducing the diameter of PSFs can also improve detection efficiency.The minimum detectable activity of the device can be further reduced using the aforementioned methods.

Chiral bound states in a staggered array of coupled resonators

We study the chiral bound states in a coupled-resonator array with staggered hopping strengths,which interacts with a two-level small atom through a single coupling point or two adjacent ones.In addition to the two typical bound states found above and below the energy bands,this system presents an extraordinary chiral bound state located within the energy gap.We use the chirality to quantify the breaking of the mirror symmetry.We find that the chirality value undergoes continuous changes by tuning the coupling strengths.The preferred direction of the chirality is controlled not only by the competition between the intracell and the intercell hoppings in the coupled-resonator array,but also by the coherence between the two coupling points.In the case with one coupling point,the chirality values varies monotonously with difference between the intracell hopping and the intercell hoppings.While in the case with two coupling points,due to the coherence between the two coupling points the perfect chiral states can be obtained.