A numerical survey of parameters to reach ignition condition for axial compression of a large-sized field reversed configuration

Field reversed configuration(FRC)is widely considered as an ideal target plasma for magnetoinertial fusion.However,its confinement and stability,both proportional to the radius,will deteriorate inevitably during radial compression.Hence,we propose a new fusion approach based on axial compression of a large-sized FRC.The axial compression can be made by plasma jets or plasmoids converging onto the axial ends of the FRC.The parameter space that can reach the ignition condition while preserving the FRC's overall quality is studied using a numerical model based on different FRC confinement scalings.It is found that ignition is possible for a large FRC that can be achieved with the current FRC formation techniques if compression ratio is greater than 50.A more realistic compression is to combine axial with moderate radial compression,which is also presented and calculated in this work.

Research on the Error Averaging Effect in A Rolling Guide Pair

By studying the e ects of geometric precision on kinematic accuracy, an error mapping model has been established, based on the hypothesis that a motion pair and its installation surface are rigid. However, when using this assumption,there is a significant error induced in high-precision computer numerical control(CNC) machine tools as compared with reality. One of the most important reasons for this error is failing to consider the error averaging e ect of motion pair elements. Therefore, this work examines a high-precision horizontal machining center as its research object, and analyzes the error averaging mechanism of a rolling guide pair under a deformation of the rolling elements. The carriage bearing forces caused by guideway straightness errors are obtained by constructing a geometric error model of a single carriage. The relationship between guideway straightness errors and carriage bearing forces is described by a transfer function in the spatial frequency domain, and its characteristics are analyzed. It quantifies the so-called error averaging e ect of the rolling guide system and, on this basis, a static model for four carriages is established to reflect the error averaging e ect of the rolling guide pair on the position and orientation errors of the motion pair. In addition, it is found that the wavelengths and phase di erences of guideway errors a ect this error averaging mechanism, but the amplitude and preload have little influence thereon. The experiment result shows that the kinematic straightness errors in the x-and y-directions were approximately 1/3 to 1/2 of the guideway straightness errors in the corresponding directions. The results can be used to guide the precision design and assembly of machine tools.

A large-grain-size thick-film polycrystalline diamond detector for x-ray detection

A diamond film with a size of 6×6×0.5 mm^3 is fabricated by electron-assisted chemical vapor deposition. Raman spectrum analysis, x-ray diffraction and scanning electron microscope images confirm the high purity and large grain size, which is larger than 300 μm. Its resistivity is higher than 10^12 W· cm. Interlaced-finger electrodes are imprinted onto the diamond film to develop an x-ray detector. Ohmic contact is confirmed by checking the linearity of its current–voltage curve. The dark current is lower than 0.1 n A under an electric field of 30 k V cm^-1. The time response is 220 ps. The sensitivity is about 125 m A W^-1 under a biasing voltage of 100 V.A good linear radiation dose rate is also confirmed. This diamond detector is used to measure x-ray on a Z-pinch, which has a double-layer 'nested tungsten wire array'. The pronounced peaks in the measured waveform clearly characterize the x-ray bursts, which proves the performance of this diamond detector.

Construction of an Hα diagnostic system and its application to determine neutral hydrogen densities on the Keda Torus eXperiment

A 10-channel Hα diagnostic system has been designed with the rapid response rate of 300 kHz, spatial resolution of about 40 mm, and overlap between adjacent channels of about 3%, and it has been implemented successfully on Keda Torus eXperiment(KTX), a newly constructed, reversed field pinch(RFP) experimental device at the University of Science and Technology of China(USTC). This diagnostic system is a very important tool for the initial KTX operations. It is compact,with an aperture slit replacing the traditional optical lens system. A flexural interference filter is designed to prevent the center wavelength from shifting too much as the increase of angle from vertical incidence. To eliminate the stray light,the interior of the system is covered with the black aluminum foil having a very high absorptivity. Using the Hαemission data, together with the profiles of electron temperature and density obtained from the Langmuir probe, the neutral density profiles have been calculated for KTX plasmas. The rapid response rate and good spatial resolution of this Hαdiagnostic system will be beneficial for many studies in RFP plasma physics.

Fast radial scanning probe system on KTX

A fast radial scanning probe system was constructed for the Keda Torus eXperiment(KTX)to measure the profiles of boundary plasma parameters such as floating potential,electron density,temperature,transport fluxes,etc.The scanning probe system is driven by slow and fast motion mechanisms,corresponding to the stand-by movement of a stepping motor and the fast scanning movement of a high-torque servo-motor,respectively.In fast scanning,the scanner drives the probe radially up to 20 cm at a maximum velocity of 4.0 m s-1.A noncontact magnetic grating ruler with a high spatial resolution of 5μm is used for the displacement measurement.New scanning probe can reach the center of plasmas rapidly.The comparison of plasma floating potential profiles obtained by a fixed radial rake probe and the single scanning probe suggests that the high-speed scanning probe system is reliable for measuring edge plasma parameter profiles on the KTX device.

Mechanical Properties and Fire Retardancy of Wood Flour/High-Density Polyethylene Composites Reinforced with Continuous Honeycomb-Like Nano-SiO_(2)Network and Fire Retardant

The mechanical properties of wood flour/high-density polyethylene composites(WPC)were improved by adding a small amount of nano-SiO_(2)to obtain a network-structured WPC with a continuous honeycomb-like nano-SiO_(2)network.The wood flour was modified with a fire retardant(a mixture of sodium octabonate and amidine urea phosphate)to improve its fire retardancy.The flexural properties,creep resistance,thermal expansion,and fire retardancy of the WPC were compared to a control(WPCCTRL)without nano-SiO_(2)or fire retardant.The flexural strength and modulus of the WPC containing only 0.55 wt.%nano-SiO_(2)were 6.6%and 9.1%higher than the control,respectively,while the creep strain and thermal expansion rate at 90°C were 33.8%and 13.6%lower,respectively.The cone calorimetry tests revealed that the nano-SiO_(2)network physically shielded the WPC,giving it lower heat release and smoke production rates.The thermal expansion was further decreased by incorporating fire retardants into the WPC,which showed the lowest total heat release and total smoke production and the highest mass retention.This study demonstrates a facile procedure for producing WPC with desired performances by forming a continuous honeycomb-like network by adding a small amount of nanoparticles.

The Realization and Working Conditions of Memristor Based on Multisim

An equivalent circuit is realized using Multisim software by transforming a kind of circuit element according to Mapping principle and circuit theory. The effects of every parameter on the equivalent circuit are analyzed and the working conditions of the equivalent circuit are concluded by simulation.

Genomic investigation and nationwide tracking of pediatric invasive nontyphoidal Salmonella in China

Impact Statement。Invasive nontyphoidal Salmonella(iNTS)causes significant concern with~15%morbidity,affecting populations mainly in African countries.

Perfect light absorber with a PT phase transition via coupled topological interface states

Recently,the concepts of parity–time(PT)symmetry and band topology have inspired many novel ideas for light manipulation in their respective directions.Here we propose and demonstrate a perfect light absorber with a PT phase transition via coupled topological interface states(TISs),which combines the two concepts in a onedimensional photonic crystal heterostructure.By fine tuning the coupling between TISs,the PT phase transition is revealed by the evolution of absorption spectra in both ideal and non-ideal PT symmetry cases.Especially,in the ideal case,a perfect light absorber at an exceptional point with unidirectional invisibility is numerically obtained.In the non-ideal case,a perfect light absorber in a broken phase is experimentally realized,which verifies the possibility of tailoring non-Hermiticity by engineering the coupling.Our work paves the way for novel effects and functional devices from the exceptional point of coupled TISs,such as a unidirectional light absorber and exceptional-point sensor.

Genomic analysis of schistosomiasis-associated colorectal cancer reveals a unique mutational landscape and therapeutic implications

The schistosomiasis-associated colorectal cancer (SA-CRC) is thought to be caused by the chronic inflammation as a result of schistosomal ova deposition in the submucosal layer of the intestine (Fig. S1). It is reported that SA-CRC differs from sporadic colorectal cancer (S-CRC) in terms of epidemiological features, histological patterns, and clinical outcomes,1 which is also supported by our institutional data (Table S1 and Fig. S2). Here we investigate the genomic alternations and probable molecular determinants of pathogenesis in Chinese SA-CRC.

超高填充聚丙烯基木塑复合材料高低温性能

为了充分降低成本,增加环境友好性并获得良好的木质感,以杨木纤维和毛竹纤维为原料,通过挤出成型制备超高填充聚丙烯基木塑复合材料(UH-WPCs)。基于聚丙烯基体含量的大幅降低,对比分析了填充量和木质纤维种类对UH-WPCs高低温力学性能、高低温蠕变性能、热膨胀性能、尺寸稳定性及吸水性能的影响。结果表明,随着填充量从75wt%增加到90wt%,其线性热膨胀系数大幅降低,蠕变应变逐渐减小而在90wt%时增大;拉伸模量和弯曲模量随填充量的增加先升高而后在90wt%时下降;拉伸强度、弯曲强度和冲击强度随着填充量的增加逐渐降低;在低温-30℃时UH-WPCs的拉伸和弯曲性能较高,高温60℃时冲击韧性较好。温度、湿度及含水率变化均导致UH-WPCs尺寸变化,其中厚度方向尺寸变化率最大,其次为宽度方向,长度方向最小,表现出明显的各向异性;湿度对UH-WPCs的尺寸稳定性的影响远大于温度的作用。杨木基UH-WPCs综合性能优于毛竹基UH-WPCs,这与杨木纤维具有更大的长径比及良好的界面结合有关。UH-WPCs的研究为降低WPCs生产成本和拓宽其应用领域提供了理论依据。

Applying rotation-invariant star descriptor to deep-sky image registration

Image registration is a critical process of many deep-sky image processing applications. Image registration methods include image stacking to reduce noise or achieve long exposure effects within a short exposure time, image stitching to extend the field of view, and atmospheric turbu- lence removal. The most widely used method for deep-sky image registration is the triangle- or polygon-based method, which is both memory and computation intensive. Deepsky image registration mainly focuses on translation and rotation caused by the vibration of imaging devices and the Earth＇s rotation, where rotation is the more difficult problem. For this problem, the best method is to find corresponding rotation-invariant features between different images. In this paper, we analyze the defects introduced by applying rotation-invariant feature descriptors to deep-sky image reg- istration and propose a novel descriptor. First, a dominant orientation is estimated from the geometrical relationships between a described star and two neighboring stable stars. An adaptive speeded-up robust features （SURF） descriptor is then constructed. During the construction of SURF, the local patch size adaptively changes based on the described star size. Finally, the proposed descriptor is formed by fusing star properties, geometrical relationships, and the adaptive SURF. Extensive experiments demonstrate that the proposed descriptor successfully addresses the gap resulting from applying the traditional feature-based method to deep-sky image registration and performs well compared to state-of-the-art descriptors.