Measurement of recoil nuclei losses for proton-induced reactions in Al, Si, Mg and Fe at 200 and 500 MeV

The recoil losses of product nuclei in proton-induced reactions at 200 and 500 MeV in Al, Si, Mg and Fe targets were measured using carbon catcher foils or stacks of Mylar foils. In all cases, the recoil losses were less than 1% for the target thicknesses used and so in the ongoing systematic study to measure cross sections for proton- and neutron-induced reactions, these losses are not important. For Fe targets irradiated at 200 MeV, the recoil losses in the forward direction for several product nuclei measured in both a carbon catcher foil and a Mylar stack were in good agreement. From the recoil losses, the mean forward recoil ranges for several product nuclei were calculated.     

一新的混凝土配筋计算方法:无量纲图表法

该文介绍作者推导的一新的主要用于混凝土梁配筋计算的无量纲通用图表法,该图表法的"新"和"通用"分别在于推导时没有用传统的"等效矩形应力"换算以及一表可适用于不同钢筋级别和不同混凝土等级(C15―C50)的配筋计算。该法扩展了《混凝土结构设计规范》的混凝土应力-应变关系的运用范围,至今只用到了混凝土的极限应变。该法计算过程简便,求得配筋后,无须再验算受压区高度,同时还可用于弯压或弯拉构件的配筋计算。计算结果中除了含有计算钢筋面积所需的内力臂系数外,还有混凝土受压区边缘应变、受拉和受压钢筋应变、混凝土受压区高度等,结果直观和一目了然,并为混凝土构件的设计提供了一新的更为精确的设计方法。     

自适应UKF在北斗伪距定位中的研究

针对北斗伪距定中噪声统计特性未知或者不准确带来的定位精度不高问题,为减小噪声统计特性的不准确在滤波过程中对状态估计带来的影响,采用了无迹卡尔曼滤波(UKF)和噪声统计值估计器相结合的滤波方法,该方法在UKF中引入改进的噪声估计Sage-Husa算法,对系统噪声和观测噪声进行实时估计,抵抗不准确噪声在定位解算时带来的误差;最后在进行状态更新时引入一个收敛因子对每一次滤波状态进行更新,保证算法的收敛性。实验结果表明,该方法与传统的无迹卡尔曼滤波相比,在提升算法收敛速度的同时,将伪距定位的精度提高了40%左右,可用于带有时变噪声和未知噪声的定位系统中。     

Two-stage Bayesian models—application to ZEDB project

A well-known mathematical tool to analyze plant specific reliability data for nuclear power facilities is the two-stage Bayesian model. Such two-stage Bayesian models are standard practice nowadays, for example in the German ZEDB project or in the Swedish T-Book, although they may differ in their mathematical models and software implementation. In this paper, we review the mathematical model, its underlying assumptions and supporting arguments. Reasonable conditional assumptions are made to yield tractable and mathematically valid form for the failure rate at plant of interest, given failures and operational times at other plants in the population. The posterior probability of failure rate at plant of interest is sensitive to the choice of hyperprior parameters since the effect of hyperprior distribution will never be dominated by the effect of observation. The methods of Pörn and Jeffrey for choosing distributions over hyperparameters are discussed. Furthermore, we will perform verification tasks associated with the theoretical model presented in this paper. The present software implementation produces good agreement with ZEDB results for various prior distributions. The difference between our results and those of ZEDB reflect differences that may arise from numerical implementation, as that would use different step size and truncation bounds.     

On computation of stabilizing loop gain and delay ranges for bi-proper delay systems

A graphical method for exactly computing the stabilizing loop gain and delay ranges was proposed [Le BN, Wang Q-G, Lee T-H. Development of D-decomposition method for computing stabilizing gain ranges for general delay systems. J Process Control 2012] for a strictly proper process by determining the boundary functions which may change system׳s stability. A bi-proper process is rare but causes great complications for the method, due to the new phenomena that do not exist for a strictly proper process, such as a non-zero gain at infinity frequency, which may cause infinite intersections of boundary functions within a finite delay range. This paper addresses such a kind of processes and develops a general method that can produce the exact and complete set of the loop gain and delay for closed-loop stabilization, which is hard to find with analytical methods.     

大开间住宅钢筋混凝土异形柱框轻结构的适用范围

通过两类计算模型、两种地震设防烈度、三种场地土类别、三种结构体系多种组合的计算与分析，提出了大开间异形柱住宅结构在天津市的适用高度、层次及最大开间尺寸建议。     

Bioinspired MXene-Based Piezoresistive Sensor with Two-stage Enhancement for Motion Capture (Adv. Funct. Mater. 18/2023)

Structured piezoresistive membranes are compelling building blocks for wearable bioelectronics. However, the poor structural compressibility of conventional microstructures leads to rapid saturation of detection range and low sensitivity of piezoresistive devices, limiting their commercial applications. Herein, a bioinspired MXene-based piezoresistive device is reported, which can effectively boost the sensitivity while broadening the response range by architecting intermittent villus-like microstructures. Benefitting from the two-stage amplification effect of this intermittent architecture, the developed MXene-based piezoresistive bioelectronics exhibit a high sensitivity of 461 kPa⁻¹ and a broad pressure detection range of up to 311 kPa, which are about 20 and 5 times higher than that of the homogeneous microstructures, respectively. Cooperating with the deep-learning algorithm, the designed bioelectronics can effectively capture complex human movements and precisely identify human motion with a high recognition accuracy of 99%. Evidently, this intermittent architecture of biomimetic strategy may pave a promising avenue to overcome the limitation of rapid saturation and low sensitivity in piezoresistive bioelectronics, and provide a general way to promote its large-scale applications.     

Rapidly Modulated Wide-Spectrum Infrared Source Made of Super Aligned Carbon Nanotube Film for Greenhouse Gas Monitoring

Non-dispersive infrared (NDIR) gas monitoring has advantages of environment stability, convenient operation and maintenance, wide detection range, and multi-gas-detection capability. However, the conventional IR sources for NDIR gas monitoring, such as miniature lamps, microelectromechanical system (MEMS) light sources, and light-emitting diodes (LEDs), can only work at narrow modulation frequency and spectral range, or require complicated design and fabrication, because of the constraint of materials and work principle. These issues cause low data acquisition rate, poor anti-interference ability and limited gas compatibility to NDIR. Here, the super-aligned carbon nanotube (SACNT) film is developed as an IR source in NDIR gas monitoring system. It has a wide spectral range (0.2–334 µm), a facile fabrication method, and can work up to a high frequency ≈150 kHz. A mechanical-chopper-free and wide-concentration-range monitoring equipment for CO₂ and CH₄ greenhouse gases is demonstrated with SACNT film IR source. The concentration ranges for CO₂ and CH₄ investigated in this paper are 0.0195–20.10% (v/v) and 0.10–17.11% (v/v), respectively. It can be easily applied to monitor other kinds of gases as well.