A novel multi-channel porous structure facilitating mass transport towards highly efficient alkaline water electrolysis

An advantageous porous architecture of electrodes is pivotal in significantly enhancing alkaline water electrolysis(AWE)efficiency by optimizing the mass transport mechanisms.This effect becomes even more pronounced when aiming to achieve elevated current densities.Herein,we employed a rapid and scalable laser texturing process to craft novel multi-channel porous electrodes.Particularly,the obtained electrodes exhibit the lowest Tafel slope of 79 mV dec^(-1)(HER)and 49 mV dec^(-1)(OER).As anticipated,the alkaline electrolyzer(AEL)cell incorporating multi-channel porous electrodes(NP-LT30)exhibited a remarkable improvement in cell efficiency,with voltage drops(from 2.28 to 1.97 V)exceeding 300 mV under 1 A cm^(-1),compared to conventional perforated Ni plate electrodes.This enhancement mainly stemmed from the employed multi-channel porous structure,facilitating mass transport and bubble dynamics through an innovative convection mode,surpassing the traditional convection mode.Furthermore,the NP-LT30-based AEL cell demonstrated exceptional durability for 300 h under 1.0 A cm^(-2).This study underscores the capability of the novel multi-channel porous electrodes to expedite mass transport in practical AWE applications.

Design of Cold-Junction Compensation and Disconnection Detection Circuits of Various Thermocouples and Implementation of Multi-Channel Interfaces Using Them-A Secondary Publication

Cold-junction compensation(CJC)and disconnection detection circuit design of various thermocouples(TC)and multi-channel TC interface circuits were designed.The CJC and disconnection detection circuit consists of a CJC semiconductor device,an instrumentation amplifier(IA),two resistors,and a diode for disconnection detection.Based on the basic circuit,a multi-channel interface circuit was also implemented.The CJC was implemented using compensation semiconductor and IA,and disconnection detection was detected by using two resistors and a diode so that IA input voltage became-0.42 V.As a result of the experiment using R-type TC,the error of the designed circuit was reduced from 0.14 mV to 3μV after CJC in the temperature range of 0°C to 1400°C.In addition,it was confirmed that the output voltage of IA was saturated from 88 mV to-14.2 V when TC was disconnected from normal.The output voltage of the designed circuit was 0 V to 10 V in the temperature range of 0°C to 1400°C.The results of the 4-channel interface experiment using R-type TC were almost identical to the CJC and disconnection detection results for each channel.The implemented multi-channel interface has a feature that can be applied equally to E,J,K,T,R,and S-type TCs by changing the terminals of CJC semiconductor devices and adjusting the IA gain.

Multi-channel terahertz focused beam generator based on shared-aperture metasurface

Most of existing metasurfaces usually have limited channel behavior,which seriouslyhinders their development and application.In this paper,we propose a multi-channel terahertz focused beam generator based on shared-aperture metasurface,and the generator consists of a top square metal strip,a middle layer of silica and a metal bottom plate.By changing the position and size of the shared-aperture array,the designed metasurface can generate any number of multi-channel focusing beams at different predicted positions.In addition,the energy intensity of focusing beams can be controlled.The full-wave simulation results show that the metasurface achieves four-channel vortex focused beam generation with different topological charges,and five-,six-,eight-channel focused beam generation with different energy intensities at a frequency of 1 THz,which are in good agreement with the theoretically calculated predictions.This work can provide a new idea for designing the terahertz multichannel devices.

Fast pre-stack multi-channel inversion constrained by seismic reflection features

Classical multi-channel technology can significantly reduce the pre-stack seismic inversion uncertainty, especially for complex geology such as high dipping structures. However, due to the consideration of complex structure or reflection features, the existing multi-channel inversion methods have to adopt the highly time-consuming strategy of arranging seismic data trace-by-trace, limiting its wide application in pre-stack inversion. A fast pre-stack multi-channel inversion constrained by seismic reflection features has been proposed to address this issue. The key to our method is to re-characterize the reflection features to directly constrain the pre-stack inversion through a Hadamard product operator without rearranging the seismic data. The seismic reflection features can reflect the distribution of the stratum reflection interface, and we obtained them from the post-stack profile by searching the shortest local Euclidean distance between adjacent seismic traces. Instead of directly constructing a large-size reflection features constraint operator advocated by the conventional methods, through decomposing the reflection features along the vertical and horizontal direction at a particular sampling point, we have constructed a computationally well-behaved constraint operator represented by the vertical and horizontal partial derivatives. Based on the Alternating Direction Method of Multipliers (ADMM) optimization, we have derived a fast algorithm for solving the objective function, including Hadamard product operators. Compared with the conventional reflection features constrained inversion, the proposed method is more efficient and accurate, proved on the Overthrust model and a field data set.

Opportunistic Routing with Multi-Channel Cooperative Neighbour Discovery

Due to the scattered nature of the network,data transmission in a dis-tributed Mobile Ad-hoc Network(MANET)consumes more energy resources(ER)than in a centralized network,resulting in a shorter network lifespan(NL).As a result,we build an Enhanced Opportunistic Routing(EORP)protocol architecture in order to address the issues raised before.This proposed routing protocol goal is to manage the routing cost by employing power,load,and delay to manage the routing energy consumption based on theflooding of control pack-ets from the target node.According to the goal of the proposed protocol techni-que,it is possible to manage the routing cost by applying power,load,and delay.The proposed technique also manage the routing energy consumption based on theflooding of control packets from the destination node in order to reduce the routing cost.Control packet exchange between the target and all the nodes,on the other hand,is capable of having an influence on the overall efficiency of the system.The EORP protocol and the Multi-channel Cooperative Neighbour Discovery(MCCND)protocol have been designed to detect the cooperative adja-cent nodes for each node in the routing route as part of the routing path discovery process,which occurs during control packet transmission.While control packet transmission is taking place during the routing path discovery process,the EORP protocol and the Multi-channel Cooperative Neighbour Discovery(MCCND)protocol have been designed to detect the cooperative adjacent nodes for each node in the routing.Also included is a simulation of these protocols in order to evaluate their performance across a wide range of packet speeds using Constant Bit Rate(CBR).When the packet rate of the CBR is 20 packets per second,the results reveal that the EORP-MCCND is 0.6 s quicker than the state-of-the-art protocols,according to thefindings.Assuming that the CBR packet rate is 20 packets per second,the EORP-MCCND achieves 0.6 s of End 2 End Delay,0.05 s of Routing Overhead Delay,120 s of Network Lifetime,and 20 J of Energy Consumption efficiency,which is much better than that of the state-of-the-art protocols.

集沙仪内二次流对沙尘收集范围的影响分析

二次流动是工程实际中普遍存在的物理现象,是一种相对于主流的次要流动。为研究集沙仪内二次流对气流速度、不同粒径的沙尘粒子的影响规律,利用数值模拟和试验验证相结合的方法,以分流对冲与多级扩容式集沙仪的风沙分离器为研究对象,对二次流被削弱前后的流场特性进行分析。研究结果表明:在二次流被削弱前,粒径大于0.083 mm的沙尘被完全收集,粒径小于0.083 mm的沙尘被大部分收集;在二次流被削弱后,高速气流分布范围更大,流场似乎变得不稳定,排气管内气流速度明显增高,粒径大于0.12 mm的沙尘才被完全收集,沙尘被完全收集的范围明显缩小。

基于透明黏土的取土器贯入扰动变形试验研究

为了解取土器贯入过程中黏土体的扰动变形特性,采用由Aristoflex AVC制成的新型透明黏土及粒子图像测速(PIV)技术,通过可视化模型试验装置进行了不同尺寸的取土器贯入试验。试验结果表明:取土器贯入过程中各截面不同位置处的土体变形规律基本一致,距离管壁越远,变形越小;取土器下部土体整体性较好,且距离中轴线约0.19倍取土器内径范围内的土体剪应变较小,室内试验可切取这部分土体;取土器贯入引起的土体扰动变形主要由侧壁摩阻力及刃脚挤土效应引起,增大取土器内径能有效减小取土器内土体的压缩变形。

基于Gibbs Sampler的线性回归模型选择

线性回归模型是计量经济学的基本模型,在建立线性回归模型的过程中,模型选择是非常重要的一个环节,如果可能的解释变量不是很多时,可以通过逐步回归的方法比较每个候选模型的准则值,如AIC、SIC等进行模型选择。可是,当存在大量可能的解释变量时,我们无法一一比较每个候选模型的准则值。为了解决这个问题,文章提出一个基于Gibbs Sampler的线性回归模型选择方法,结果表明应用该方法能够从大量候选模型中准确、高效地确认准则值最小的模型。

基于集成重要性采样的随机梯度下降算法

许多机器学习和深度学习问题都可以使用随机梯度优化算法求解,目前流行的算法大多通过均匀采样从样本集中抽取样本计算梯度估计。然而,随机采样的梯度估计会带来较大的方差,这个方差会随着优化的进行而累积,降低算法收敛速度。为缓解这一现象,可以为每个样本赋予不同的采样概率。该文基于集成学习的思想,提出了一种新的选取非均匀采样分布的算法。算法的主要目的是选取一个采样器权重,使梯度估计的方差尽可能小。所提算法由多个简单采样器组成,采样权重为每个简单采样器分配贡献权重,从而得到最终的采样分布。集成重要性采样算法可以和以往的随机梯度优化方法任意结合,该文给出了使用集成重要性采样的随机梯度下降算法。在试验中,可以直观地看到算法起效的原因。在真实数据集中,展示了所提算法减小方差的效果,与其他算法相比具有一定优势。

基于Bayesian Gibbs Sampler的状态空间模型估计方法研究及其在中国潜在产出估计上的应用

本文将贝叶斯吉伯斯样本生成(Bayesian Gibbs Sampling,BGS)方法应用到状态空间模型的估计。首先介绍了BGS方法的基本内容和计算步骤,然后给定参数生成满足状态空间模型的模拟数据,并对模拟数据应用BGS方法估计。结果表明参数和状态向量的估计值与参数和状态向量的真实值相当接近,明显优于基于Kalman滤波的最大似然估计结果。最后,本文将BGS算法应用于中国1980至2008年的潜在增长率与增长率缺口的估计。

一种改进的黑土农田风蚀集沙仪

风蚀监测可反映风沙运动规律,集沙仪是风蚀监测的必备仪器,而以往研究大多在沙漠或沙地开展,较少涉及黑土农田。本研究基于BSNE(Big Spring Number Eight)集沙仪,将采沙盒底部阻风结构中的18目孔径筛网改进为逆向百叶窗式的阻风挡板,采用模拟试验对比分析BSNE集沙仪和改进后rBSNE(Revised Spring Number Eight)集沙仪的保沙和集沙能力,并将其应用于野外黑土农田风蚀监测。研究结果表明:与BSNE集沙仪相比,rBSNE集沙仪降低了小粒级颗粒的损失率,当风速低于20 m·s^(-1)时,对<0.25 mm粒径的土壤颗粒的损失率显著降低74.3%~87.1%;当风速达到20 m·s^(-1)时,对所有试验粒径的土壤颗粒的损失率显著降低46.9%~74.3%。与BSNE集沙仪相比,rBSNE集沙仪有助于对小粒级颗粒的收集,当风速低于20 m·s^(-1)时,对粒径为<0.5 mm的集沙量显著增加了9.0%~44.0%;当风速达到20 m·s^(-1)时,对所有试验粒径的集沙量均显著增加7.3%~34.4%。野外监测结果显示风蚀输沙量随高度增加呈指数函数递减趋势,说明rBSNE集沙仪可应用于黑土农田风蚀的监测。

一种用于宽带取样示波器的幅值校准方法

取样示波器采用顺序等效采样原理,可以实现对高速稳定信号进行采样、波形恢复、信号质量分析等,在高速通信、信息对抗等领域有广泛应用。但作为取样示波器核心器件的取样器,采用双肖特基二极管对称结构,因器件、布局布线等非对称性,导致差分输出的两路信号存在偏差等,造成测量波形的不准确。为更加准确地重建被测信号的真实值,提出一种基于最小二乘法的二进制幅值校准方法。通过实验验证,此方法能够准确计算校准系数,实现对幅值的校准,相对误差在1%以内,并且在采样点数较少的情况下仍然适用。结果表明,此方法可以用于宽带取样示波器的幅值校准。

扦样机混样模块的有限元分析

中国作为粮食大国,历来重视粮食储存安全问题。目前,国内粮库一般使用扦样机对仓内粮食进行抽样检测,但是准确率较低。因此,高质量的扦样设备更能保证粮食检测结果的准确性。以电机驱动的扦样机的混样模块为研究课题,主要研究任务是对该混样模块进行有限元分析,主要研究任务有以下几个部分:使用EDEM离散元软件,确定工作过程中各部件的受力大小;将混样模块的模型导入进有限元分析软件中,对其进行前处理;分析该模块的受力情况,并提取其中最容易断裂的搅拌叶片进行更精细的有限元分析。

基于协变量的一类贝叶斯社区检测算法

在复杂网络系统研究中,社区检测是挖掘网络数据内部结构信息的重要方法之一。提出了一个含有节点协变量信息的度修正随机块模型的贝叶斯社区检测算法,通过基于随机森林的算法选择重要的节点协变量,应用与协变量相关的随机划分模型划分社区隶属度,应用DCSBM模型,通过Gibbs采样方法进行社区检测并推断社区数量。数值模拟结果表明含有节点协变量信息的度修正随机块模型的贝叶斯社区检测算法可以显著提高社区检测的性能。最后将含有节点协变量信息的度修正随机块模型的贝叶斯社区检测算法方法应用到Weddell Sea营养网络的实际数据进行实证分析。

半参数双重Tweedie复合泊松回归模型的贝叶斯分析

为了分析健康保险行业中出现的半连续卫生保健费用数据,本文提出一类半参数双重Tweedie复合泊松回归模型.在分析中,首先采用修正鞍点逼近的数值方法去近似Tweedie复合泊松分布的密度函数;其次,利用Gibbs抽样技术和Metropolis-Hastings(MH)算法的混合算法获得了模型参数的联合贝叶斯估计;最后,给出了几个模拟研究以及把这些方法用来分析兰德健康保险实验中的卫生保健费用数据.

复杂基质环境中长时间维度被动采样装置的研发与评估——以污水管网中精神活性物质的监测为例

精神活性物质(Psychoactive Substance,PAS)的非法滥用是人类发展面临的难题,快速高效地评估毒情是解决这一难题的基础,及时获取时间加权浓度、低成本的被动采样技术日益受到关注。本研究基于混合型阳离子交换树脂吸附剂开发了一种新型被动采样装置,并应用于污水管网中PAS的快速监测。探讨了采样条件对甲基苯丙胺、3,4-亚甲二氧基甲基苯丙胺、氯胺酮、去甲氯胺酮、吗啡和可替宁采样率(Sampling Rates,RS)的影响。结果表明,温度和pH对RS的影响较大,流速和溶解性有机物的影响不明显。温度改变时,6种PAS的RS的平均变化为0.195 L·d^(−1);pH改变时,6种PAS的RS的平均变化为0.171 L·d^(−1);流速改变时,6种PAS的RS的平均变化为0.057 L·d^(−1);溶解性有机物浓度改变时,6种PAS的RS的平均变化为0.094 L·d^(−1)。实验室模拟阳性环境下,采用胶体金法快速检测采样装置洗脱液中的PAS,3次实验结果均呈阳性,验证了该方法的可靠性。

Comparison of methods for deriving phenotypes from incomplete observation data with an application to age at puberty in dairy cattle

Background Many phenotypes in animal breeding are derived from incomplete measures,especially if they are challenging or expensive to measure precisely.Examples include time-dependent traits such as reproductive status,or lifespan.Incomplete measures for these traits result in phenotypes that are subject to left-,interval-and rightcensoring,where phenotypes are only known to fall below an upper bound,between a lower and upper bound,or above a lower bound respectively.Here we compare three methods for deriving phenotypes from incomplete data using age at first elevation(>1 ng/mL)in blood plasma progesterone(AGEP4),which generally coincides with onset of puberty,as an example trait.Methods We produced AGEP4 phenotypes from three blood samples collected at about 30-day intervals from approximately 5,000 Holstein–Friesian or Holstein–Friesian×Jersey cross-bred dairy heifers managed in 54 seasonal-calving,pasture-based herds in New Zealand.We used these actual data to simulate 7 different visit scenarios,increasing the extent of censoring by disregarding data from one or two of the three visits.Three methods for deriving phenotypes from these data were explored:1)ordinal categorical variables which were analysed using categorical threshold analysis;2)continuous variables,with a penalty of 31 d assigned to right-censored phenotypes;and 3)continuous variables,sampled from within a lower and upper bound using a data augmentation approach.Results Credibility intervals for heritability estimations overlapped across all methods and visit scenarios,but estimated heritabilities tended to be higher when left censoring was reduced.For sires with at least 5 daughters,the correlations between estimated breeding values(EBVs)from our three-visit scenario and each reduced data scenario varied by method,ranging from 0.65 to 0.95.The estimated breed effects also varied by method,but breed differences were smaller as phenotype censoring increased.Conclusion Our results indicate that using some methods,phenotypes derived from one observation per offspring for a time-dependent trait such as AGEP4 may provide comparable sire rankings to three observations per offspring.This has implications for the design of large-scale phenotyping initiatives where animal breeders aim to estimate variance parameters and estimated breeding values(EBVs)for phenotypes that are challenging to measure or prohibitively expensive.

Parametric study on contact sensors for MASW measurement-based interfacial debonding detection for SCCS

Steel-concrete composite structures(SCCS)have been widely used as primary load-bearing components in large-scale civil infrastructures.As the basis of the co-working ability of steel plate and concrete,the bonding status plays an essential role in guaranteeing the structural performance of SCCS.Accordingly,efficient non-destructive testing(NDT)on interfacial debondings in SCCS has become a prominent research area.Multi-channel analysis of surface waves(MASW)has been validated as an effective NDT technique for interfacial debonding detection for SCCS.However,the feasibility of MASW must be validated using experimental measurements.This study establishes a high-frequency data synchronous acquisition system with 32 channels to perform comparative verification experiments in depth.First,the current sensing approaches for high-frequency vibration and stress waves are summarized.Secondly,three types of contact sensors,namely,piezoelectric lead-zirconate-titanate(PZT)patches,accelerometers,and ultrasonic transducers,are selected for MASW measurement.Then,the selection and optimization of the force hammer head are performed.Comparative experiments are carried out for the optimal selection of ultrasonic transducers,PZT patches,and accelerometers for MASW measurement.In addition,the influence of different pasting methods on the output signal of the sensor array is discussed.Experimental results indicate that optimized PZT patches,acceleration sensors,and ultrasonic transducers can provide efficient data acquisition for MASW-based non-destructive experiments.The research findings in this study lay a solid foundation for analyzing the recognition accuracy of contact MASW measurement using different sensor arrays.

基于Multi-Radio Multi-Channel传感器网络无冲突信道分配算法的研究

为降低通信冲突和信道干扰,对Mult-i Radio Mult-i Channel传感器网络无冲突信道进行研究,结果证实在网络通信半径大于3倍的网络最大功率通信半径的前提下,Sensor节点规模满足2倍网络功率级数加1的环境下,网络无冲突信道分配的信道数达到网络信道冲突图的最大值。文章通过对无冲突信道算法的运用,最终证实其可以有效地提高传感器网络的工作效率,大幅度提升网络的吞吐量。

小型农田原状土样采集机器人系统研发与测试

农业机器人是农业机械领域的研究热点之一。国内外对温室/农田/果园作业(除草、施肥、喷药、采摘等)机器人移动平台的研究已取得初步成果,但对农田土样采集机器人移动平台的研究鲜有出现。在土壤的物理力学特性研究过程中,原状土壤样品的采集是一个重要前提。如果土样的原状度无法保障,后期实验室物理力学测试分析难以得出准确的研究结果。本研究针对这一问题,研发了一台结构紧凑、通过性强、取土质量好、取土效率高的农田土壤采集机器人移动平台,给出了机械系统、控制系统设计方案,并开展了初步的田间试验研究。本研究的主要内容如下:(1)机器人移动平台本体设计方面,确定了差速转向的转向方式;进行了机械系统设计,完成了相关硬件选型分析和控制系统设计以及软件编写。移动平台轴距为960 mm、轮距为600 mm,轮毂电机功率1000 W,实现了基于调速转把和遥控手柄的移动平台协调运动控制,满足试验要求。(2)土样采集装置方面,对分段原状取土装置进行了设计。通过对比分析选用液压传动作为动力源和直压旋入式入土方式。通过理论分析确定了取土器主要技术参数,并对其入土关键部件进行有限元分析,验证了其结构参数设计的合理性。(3)通过田间试验,考察整机的移动性能和取土质量。移动性能测试试验结果表明:最大垂直越障高度80 mm,最大爬坡坡度35°。土样抗剪强度检测试验结果表明:在获取0~200 mm深度土样时,环刀法和新系统所取土样的内摩擦角方差在0.05的置信水平下,P值等于0.866;在获取0~100 mm和100~200 mm深度土样时,环刀法和取土装置所取土样的凝聚力方差在0.05的置信水平下,P值分别为0.145和0.717。取土效率对比试验结果表明:该取土装置完成一次取土仅需3~5 min。