Optimal preparation of Bose and Fermi atomic gas mixtures of ^(87)Rb and ^(40)K in a crossed optical dipole trap

We report on the optimal production of the Bose and Fermi mixtures with ^(87) Rb and ^(40)K in a crossed optical dipole trap(ODT).We measure the atomic number and lifetime of the mixtures in combination of the spin state |F=9/2,m_F=9/2) of^(40)K and |1,1>of ^(87) Rb in the ODT,which is larger and longer compared with the combination of the spin state 19/2,9/2) of^(40)K and 12,2) of ^(87)Rb in the ODT.We observe the atomic numbers of ^(87)Rb and ^(40)K shown in each stage of the sympathetic cooling process while gradually reducing the depth of the optical trap.By optimizing the relative loading time of atomic mixtures in the MOT,we obtain the large atomic number of ^(40)K(~6 ×10^(6)) or the mixtures of atoms with an equal number(~1.6 × 10^(6)) at the end of evaporative cooling in the ODT.We experimentally investigate the evaporative cooling in an enlarged volume of the ODT via adding a third laser beam to the crossed ODT and found that more atoms(8 × 10^(6)) and higher degeneracy(T/T_(F)=0.25) of Fermi gases are obtained.The ultracold atomic gas mixtures pave the way to explore phenomena such as few-body collisions and the Bose-Fermi Hubbard model,as well as for creating ground-state molecules of ^(87)Rb^(40)K.

Quantum degenerate Bose–Fermi atomic gas mixture of 23Na and 40K

We report a compact experimental setup for producing a quantum degenerate mixture of Bose23Na and Fermi40K gases. The atoms are collected in dual dark magneto–optical traps(MOT) with species timesharing loading to reduce the light-induced loss, and then further cooled using the gray molasses technique on the D2line for23Na and D1line for40K. The microwave evaporation cooling is used to cool23Na in |F = 2, mF= 2〉 in an optically plugged magnetic trap, meanwhile,40K in |F = 9/2, mF= 9/2〉 is sympathetically cooled. Then the mixture is loaded into a large volume optical dipole trap where23Na atoms are immediately transferred to |1, 1〉 for further effective cooling to avoid the strong three-body loss between23Na atoms in |2, 2〉 and40K atoms in |9/2, 9/2〉. At the end of the evaporation in optical trap, a degenerate Fermi gas of40K with 1.9 × 10^(5) atoms at T/TF= 0.5 in the |9/2, 9/2〉 hyperfine state coexists with a Bose–Einstein condensate(BEC) of23Na with 8 × 10^(4) atoms in the |1, 1〉 hyperfine state at 300 n K. We also can produce the two species mixture with the tunable population imbalance by adjusting the 23Na magneto–optical trap loading time.

基于BP神经网络算法的固体有机肥撒施装置控制系统设计

为保证大田有机肥撒施量精确可控,符合大田作物生长需求,设计一个基于BP神经网络算法的固体有机肥撒施装置控制系统。该系统配套设备采用链板及挡肥板配合控制撒肥量的固体有机肥撒施机,控制系统以数据采集与监视控制系统(SCADA)为核心,人机交互由触摸屏实现。通过输入大田基础肥料需求量为控制算法提供基础数据,结合车辆行进速度,采用动量BP神经网络算法先行对挡肥板开度进行控制并为输肥链板转速控制提供输入值,再利用弹性BP神经网络算法对及链板转速进行控制。实验结果表明,控制系统能够根据设定的基础肥料需求量及车辆行进速度,实时改变挡肥板开度及撒肥机链板转速,撒肥量控制偏差小于9%。

Achieving ultracold Bose–Fermi mixture of^(87)Rb and^(40)K with dual dark magnetic-optical-trap

We demonstrate that dual dark magnetic-optical-traps(MOTs)have great importance in the two-species^(87)Rb and^(40)K mixture compared with dual bright MOTs.The dark MOT has a little improvement in the trapping of single-species^(87)Rb or^(40)K gases compared with bright MOT.For the case of loading two-species^(87)Rb and^(40)K simultaneously,the improvement of^(40)K in the dual dark MOTs is mainly from the reduction of light-assisted collision losses.The dual dark MOTs employ a pair of conical lenses to produce the hollow beam for repump laser with high efficiency.The number and density of^(87)Rb and^(40)K atoms after evaporative cooling in the hybrid magnetic trap with dark MOT loading are compared with those in bright MOT.The atoms with large number and high density make it easier to realize the quantum degenerate of Bose-Fermi mixture.

Experimental realization of two-dimensional single-layer ultracold gases of ^(87)Rb in an accordion lattice

We experimentally realize two-dimensional(2D) single-layer ultracold gases of ^(87)Rb by dynamically tuning the periodicity of a standing wave, known as accordion lattice. In order to load ^(87)Rb Bose-Einstein condensate into single dark fringe node of the blue detuning optical lattice, we reduce the lattice periodicity from 26.7 μm to 3.5 μm with the help of an acousto-optic deflector(AOD) to compress the three-dimensional BEC adiabatically into a flat and uniform quasi-2D single-layer. We describe the experimental procedure of the atoms loading into the accordion lattice in detail and present the characteristics of the quasi-2D ultracold gases. This setup provides an important platform for studying in-and out-of equilibrium physics, phase transition and 2D topological matter.

Ultra-compact and broadband polarization-insensitive mode-order converting power splitter

A polarization-insensitive mode-order converting power splitter using a pixelated region is presented and investigated in this paper.As TE_(0)and TM_(0)modes are injected into the input port,they are converted into TE_(1)and TM_(1)modes,which evenly come out from the two output ports.The finite-difference time-domain method and direct-binary-search optimization algorithm are utilized to optimize structural parameters of the pixelated region to attain small insertion loss,low crosstalk,wide bandwidth,excellent power uniformity,polarization-insensitive property,and compact size.Experimental results reveal that the insertion loss,crosstalk,and power uniformity of the fabricated device at 1550 nm are 0.57,-19.67,and 0.094 d B in the case of TE polarization,while in the TM polarization,the relevant insertion loss,crosstalk,and power uniformity are 0.57,-19.40,and 0.11 d B.Within a wavelength range from 1520 to 1600 nm,for the fabricated device working at TE polarization,the insertion loss,crosstalk,and power uniformity are lower than 1.39,-17.64,and 0.14 dB.In the case of TM polarization,we achieved an insertion loss,crosstalk,and power uniformity less than 1.23,-17.62,and 0.14 dB.

Experimental demonstration of a flexible-grid 1×(2×3)mode-and wavelength-selective switch using silicon microring resonators and counter-tapered couplers

A flexible-grid 1×(2×3)mode-and wavelength-selective switch which comprises counter-tapered couplers and silicon microring resonators has been proposed,optimized,and demonstrated experimentally in this work.By carefully thermally tuning phase shifters and silicon microring resonators,mode and wavelength signals can be independently and flexibly conveyed to any one of the output ports,and different bandwidths can be generated as desired.The particle swarm optimization algorithm and finite difference time-domain method are employed to optimize structural parameters of the twomode(de)multiplexer and crossing waveguide.The bandwidth-tunable wavelength-selective optical router composed of12 microring resonators is studied by taking advantage of the transfer matrix method.Measurement results show that,for the fabricated module,cross talk less than-10.18 dB,an extinction ratio larger than 17.41 d B,an in-band ripple lower than0.79 dB,and a 3-dB bandwidth changing from 0.38 to 1.05 nm are obtained,as the wavelength-channel spacing is 0.40 nm.The corresponding response time is measured to be 13.64μs.

Double Mutational Salp Swarm Algorithm:From Optimal Performance Design to Analysis

The Salp Swarm Algorithm(SSA)is a population-based Meta-heuristic Algorithm(MA)that simulates the behavior of a group of salps foraging in the ocean.Although the basic SSA has stable exploration capability and convergence speed,it still can fall into local optimum when solving complex optimization problems,which may be due to low utilization of population information and unbalanced exploration-to-exploitation ratio.Therefore,this study proposes a Double Mutation Salp Swarm Algorithm(DMSSA).In this study,a Cuckoo Mutation Strategy(CMS)and an Adaptive DE Mutation Strategy(ADMS)are introduced into the structure of the original SSA.The former mutation strategy is summarized as three basic operations:judgment,shuffling,and mutation.The purpose is to fully consider the information among search agents and use the differences between different search agents to participate in the update of positions,making the optimization process both diverse in exploration and minor in randomness.The latter strategy employs three basic operations:selection,mutation,and adaptation.As the follower part,some individuals do not blindly adopt the original follow method.Instead,the global optimal position and differences are considered,and the variation factor is adjusted adaptively,allowing the new algorithm to balance exploration,exploitation,and convergence efficiency.To evaluate the performance of DMSSA,comparisons are made with numerous algorithms on 30 IEEE CEC2014 benchmark functions.The statistical results confirm the better performance and significant difference of DMSSA in solving benchmark function tests.Finally,the applicability and scalability of DMSSA to optimization problems with constraints are further confirmed in three experiments on classical engineering design optimization problems.The source code of the proposed algorithm will be available at:https://github.com/ncjsq/Double-Mutational-Salp-Swarm-Algorithm.

A Boosted Communicational Salp Swarm Algorithm: Performance Optimization and Comprehensive Analysis

The Salp Swarm Algorithm (SSA) is a recently proposed swarm intelligence algorithm inspired by salps, a marine creature similar to jellyfish. Despite its simple structure and solid exploratory ability, SSA suffers from low convergence accuracy and slow convergence speed when dealing with some complex problems. Therefore, this paper proposes an improved algorithm based on SSA and adds three improvements. First, the Real-time Update Mechanism (RUM) underwrites the role of ensuring that excellent individual information will not be lost and information exchange will not lag in the iterative process. Second, the Communication Strategy (CMS), on the other hand, uses the multiplicative relationship of multiple individuals to regulate the exploration and exploitation process dynamically. Third, the Selective Replacement Strategy (SRS) is designed to adaptively adjust the variance ratio of individuals to enhance the accuracy and depth of convergence. The new proposal presented in this study is named RCSSSA. The global optimization capability of the algorithm was tested against various high-performance and novel algorithms at IEEE CEC 2014, and its constrained optimization capability was tested at IEEE CEC 2011. The experimental results demonstrate that the proposed algorithm can converge faster while obtaining better optimization results than traditional swarm intelligence and other improved algorithms. The statistical data in the table support its optimization capabilities, and multiple graphs deepen the understanding and analysis of the proposed algorithm.

Investigation of distribution uniformity of distributor for biogas slurry application based on CFD analysis

A horizontal distributor for biogas slurry application was proposed to explore the distribution performance through CFD analysis and verified by field test.The rheological properties of biogas slurry were analyzed at first,and key parameters were obtained for the next simulation.The effects of distribution modes,inlet direction,and outlets number on the velocity distribution of flow field and mass flow rate of the horizonal distributor were investigated by CFD simulations.Results of rheological properties indicated that biogas slurry was a non-Newtonian fluid and exhibited shear-thinning behavior.It can be well described by power-law model.The simulation results showed that the geometry of rotor,especially the block numbers was the main factor that determining the fluid movement and trajectory of distribution and output.The mode rotor 1 with two blocks reached the lowest variable coefficient of mass flow rate(4.49%),indicating a higher degree of uniformity.The upward inlet direction would obtain less dead zone,and the distributor with an even outlets number would possess more uniform distribution and less dead zone.The field test of the distributor with rotor 1,upward inlet direction,and 24 outlets has been carried on to verify the simulation results,the variable coefficient of mass flow was 13.06%,which was slightly higher than the simulation(9.23%),but it still within the range of requirement(<15%).The proposed model and the findings of this work are of guiding significance for the study of the utilization technology and equipment of liquid biogas residue.

An isolated SNM model for high-stability multi-port register file in 65 nm CMOS

In modern microprocessors, the multi-port register file is one of the key modules which provides fast and multiple data access for instructions. As the number of access ports in register files increases, stability becomes a key issue due to the voltage fluctuation on bit lines. We propose to apply an isolated inverter to address the voltage fluctuation. To assess the register stability, we derive a closed-form expression of static noise margin （SNM） for our register file. The proposed SNM model can be used as a guideline to predict the impact of several register parameters on the stability and optimize register file designs. To validate the proposed SNM model, we fabricated a test chip of two-write-four-read （2W4R） 1024 bits register file in a TSMC 65 nm low-power CMOS technology. The experimental result shows that the stability of our register file cells with an isolated inverter improve the conventional cells by approximately 2.4 times. Also, the supply voltage causes a fluctuation of SNM of about 65%, while temperature and transistor mismatch cause a fluctuation of SNM of about 20%.

A low standby-power fast carbon nanotube ternary SRAM cell with improved stability

Power dissipation, speed and stability are the most important parameters for multiple-valued SRAM design. To reduce the power consumption and further improve the performance of the ternary SRAM cell, we propose a low standby-power fast ternary SRAM cell based on carbon nanotube field effect transistors(CNFETs).The performance is simulated in terms of three criteria including standby-power, delay(write and read) and stability(RSNM). Compared to the novel ternary SRAM cell, our results show that the average standby-power, write and read delay of the proposed cell are reduced by 78.1%, 39.6% and 58.2%, respectively. In addition, the RSNM under process variations is 2.01× and 1.95× of the conventional and novel ternary SRAM cells, respectively.

The molecular,electrophysiological,and structural changes in the vestibular nucleus during vestibular compensation:a narrative review

The vestibular system involves high-level sensory and cognitive processes,such as spatial perception,balance control,visual stability,and emotional control.Vestibular dysfunction can induce vertigo,blurred vision,postural imbalance,walking instability,and spatial discomfort,which causes serious damage to health.It has long been known that after peripheral vestibular lesion,vestibular dysfunction may spontaneously recover.This is known as vestibular compensation.However,at least 20%to 30%of patients with vestibular disorders cannot yield vestibular compensation and remain with vestibular dysfunction for the rest of their lives.The exploration of the biological characteristics and regulatory factors of the loss and reestablishment of vestibular function will establish a new understanding of the mechanism of vestibular compensation and provide new tools and strategies for promoting vestibular rehabilitation.We aim to comprehensively review the mechanism of vestibular compensation and discuss future directions in this field.

High speed true random number generator with a new structure of coarse-tuning PDL in FPGA

A metastability-based TRNG（true random number generator） is presented in this paper, and implemented in FPGA. The metastable state of a D flip-flop is tunable through a two-stage PDL（programmable delay line）.With the proposed coarse-tuning PDL structure, the TRNG core does not require extra placement and routing to ensure its entropy. Furthermore, the core needs fewer stages of coarse-tuning PDL at higher operating frequency,and thus saves more resources in FPGA. The designed TRNG achieves 25 Mbps @ 100 MHz throughput after proper post-processing, which is several times higher than other previous TRNGs based on FPGA. Moreover, the robustness of the system is enhanced with the adoption of a feedback system. The quality of the designed TRNG is verified by NIST（National Institute of Standards and Technology） and also accepted by class P1 of the AIS-20/31 test suite.