Computerised Gate Firing Control for 17-Level MLI using Staircase PWM

A basic 7-level MLI topology is developed and the same is extended to the 9-level then further increased to 17-levels.The developed structure minimizes the component’s count and size to draw out the system economy.Despite the various advantages of MLIs,efficiency and reliability play a major role since the usage of components is higher for getting a low Total Harmonics Distortion(THD)value.This becomes a major challenge incorporated in boosting the efficiency without affecting the THD value.Various parametric observations are done and realized for the designed 9-level and 17-level MLI,being the Total Standing Voltage(TSV),efficiency,cost function per level count,and power loss.The respective parameters are compared with several existing and modern circuits and found to be effective in their performance.A novel single-phase 17-level asymmetrical Multi-Level Inverter(MLI)topology is developed to reduce the number of overall components.The developed topology generates 17-levels by using unequal DC sources.The developed MLI is proved under various tests con-ducted experimentally for the various loads like resistive,inductive,and combinational loads.A detailed comparison is done on several factors and represented graphically represented.Further,the proposed design provides a less TSV value is 6 V_(dc),efficiency is 94.21%and cost factor per level CF/L value for both values ofαis 2.01 and 2.05 and devices count with a low THD value 41.4%with respectively.

Seismic performance analysis and design suggestion for frame buildings with cast-in-place staircases

Many staircases in reinforced concrete （RC） frame structures suffered severe damage during the Wenchuan earthquake. Elastic analyses for 18 RC structure models with and without staircases are conducted and compared to study the influence of the staircase on the stiffness, displacements and internal forces of the structures. To capture the yielding development and damage mechanism of frame structures, elasto-plastic analysis is carried out for one of the 18 models. Based on the features observed in the analyses, a new type of staircase design i.e., isolating them from the master structure to eliminate the effect of K-type struts, is proposed and discussed. It is concluded that the proposed method of staircase isolation is effective and feasible for engineering design, and does not significantly increase the construction cost.

A Prelude Staircase to a Type V Intermittency in Two—Dimensional Discontinuous Maps

A sequence of periodic attractors has been observed in a two-dimensional discontinuous map, which canbe considered as a model of impact oscillator. The so-called 'transfer number', which is defined as the mean numberof transfer from non-impact state to impact state per iteration, is locked onto a lot of rational values to form a curveconsisting of many steps. Our numerical investigation confirms that every step is confined by conditions created by thecollision between the periodic orbit and the discontinuous boundary of the system. After the last collision the systemshows a chaotic motion with intermittent characteristics. Therefore the staircase can be addressed as a 'prelude staircaseto type V intermittency'. The similar phenomenon has also been observed in a model of electric circuit. These resultsof our study suggest that this kind of staircases is common in two (or even higher) dimensional discontinuous maps.

Non-linear Invertible Maps that Preserve Staircase Subalgebras

Let g be the general linear Lie algebra consisting of all n x n matrices over a field F and with the usual bracket operation {x, y} =xy - yx. An invertible map φ ： g →g is said to preserve staircase subalgebras if it maps every staircase subalgebra to some staircase subalgebra of the same dimension. In this paper, we devote to giving an explicit description on the invertible maps on g that preserve staircase subalgebras.

Improving the Seismic Performance of Staircases in Building Structures with a Novel Isolator

A staircase provides the main escape way from a building in an emergency.Unfortunately,it may suffer severe damages or even collapse during an earthquake.For improving the seismic performance of staircases,this paper proposes an innovative staircase isolator with the features of lightweight,costeffective and ease of construction and replacement,which is formed by suitable engineering plastic shims between rubber layers.A connection construction scheme is also proposed for the isolated staircase.Systematic performance tests have been carried out to characterize the isolator in terms of mechanic behavior and ultimate states.The test results show that mechanical properties of the proposed staircase isolator are excellent and suitable for staircase in building structure.In order to investigate the influence of staircase on building structural responses,time history analyses of a typical building structure without staircase(WS),with fixed staircase(FS)and with isolated staircase(IS)are conducted and compared within the environment of SAP2000.Results show that staircase isolation can effectively eliminate the diagonal bracing effect of staircase slab and make structural components uniformly stressed.When the novel isolator is employed for staircase in a building structure,there is no vulnerable position in staircase and the performance of staircase in building structure can be greatly enhanced.

Adaptability of Conservative Staircase Scheme for Live Videos

Existing broadcasting schemes provide services for the stored videos. The basic approach in these schemes is to divide the video into segments and organize them over the channels for proper transmission. Some schemes use segments as a basic unit, whereas the others require segments to be further divided into subsegments. In a scheme, the number of segments/subsegments depends upon the bandwidth allocated to the video by the video server. For constructing segments, the video length should be known. If it is unknown, then the segments cannot be constructed and hence the scheme cannot be applied to provide the video services. This is an important issue especially in live broadcasting applications wherein the ending time of the video is unknown, for example, cricket match. In this paper, we propose a mechanism for the conservative staircase scheme so that it can support live video broadcasting.

Quantum Conductance Staircase of Edge Hole Channels in Silicon Quantum Wells

We present the findings for the quantum conductance staircase of holes that is caused by the edge channels in the ultra-shallow p-type silicon quantum well (Si-QW), 2 nm, confined by the δ-barriers heavily doped with boron on the n-type Si (100) surface. This longitudinal quantum conductance staircase, Gxx, is revealed by the voltage applied to the Hall contacts, Vxy, to a maximum of 4e2/h. In addition to the standard plateau, 2e2/h, the variations of the Vxy voltage appear to exhibit the fractional forms of the quantum conductance staircase with the plateaus and steps that bring into correlation respectively with the odd and even fractional values.

Asymptotically Necessary and Sufficient Quadratic Stability Conditions of T-S Fuzzy Systems Using Staircase Membership Function and Basic Inequality

Asymptotically necessary and sufficient quadratic stability conditions of Takagi-Sugeno (T-S) fuzzy systems are obtained by utilizing staircase membership functions and a basic inequality. The information of the membership functions is incorporated in the stability analysis by approximating the original continuous membership functions with staircase membership functions. The stability of the T-S fuzzy systems was investigated based on a quadratic Lyapunov function. The asymptotically necessary and sufficient stability conditions in terms of linear matrix inequalities were derived using a basic inequality. A fuzzy controller was also designed based on the stability results. The derivation process of the stability results is straightforward and easy to understand. Case studies confirmed the validity of the obtained stability results.

Nuclear-Magnetic-Resonance Properties of the Staircase Kagome Antiferromagnet PbCu3TeO7

We report the first nuclear magnetic resonance （NMR） study on single crystals of staircase Kagome antiferromagnet PbCu3Te07 （TN1 -36K）. A Curie constant θ -140K is obtained by a Curie Weiss fit to the high- temperature Knight shift of 125 Te. The hyperfine coupling constant is estimated to be 125Ahf = -67 kOe/#B, and a strong interlayer coupling among staircase Kagome planes is suggested with such a large hyperfine coupling, according to the lattice structure. The 63,65Cu NMR spectra are found by the zero-field （ZF） NMR at T = 2 K, and the internal hyperfine fields are estimated to be 10.3 T and 9.6 T, for Cu（1） and Cu（2） sites, respectively, in the lattice. A second type of ZF NMFt signal with a large rf enhancement is also seen after field-cycling through a high magnetic field.

User Preference Survey on Staircase Rotation

Staircase is an important means of vertical transportation. Staircase design exerts a great influence on the aesthetics, transportation efficiency, user comfort and experience level. In this paper, a survey on the staircase rotation preference was conducted, based on the environment behavior studies. Different user frequencies of a pair of scissors stairs in the 2nd teaching building of North China University of Technology were analyzed. The psychological effect was evaluated and quantified, and the user preference on the two staircase rotations was then withdrawn. The survey found that the type of staircase with clockwise upstairs was much more preferred （78%） than the other staircase rotation anti-clock upstairs. Considering different genders, the female shows a 66% higher preference inclination of this type of staircase rotation than the male. To improve the transportation efficiency of the staircase in case of fire, the result of this paper can be very constructive for the evacuation staircase rotation choice for the high-rise buildings.

杭州电竞中心基础及地下室设计

杭州电竞中心项目采用桩基、筏板基础等多种基础形式,采用YJK软件进行多种基础形式之间的沉降差计算,并提出多种基础形式运用于同一建筑物时的加强措施。对于三面覆土、一面开敞地下室的不平衡水、土压力问题,利用桩基抵抗不平衡水、土压力,并提出相应的加强措施。将抗拔桩、无粘结预应力抗浮锚杆以及排水泄压多种抗浮技术应用于本工程,基于连通器原理的排水泄压主动抗浮技术的应用,大大减少抗浮锚杆的数量,获得了良好的经济效应;对于工程中多向框架梁与斜柱的连接节点,采用圆形柱帽有效约束各个方向相交的框架梁,并采用ABAQUS进行了有限元分析来模拟其受力性能,证明连接节点的可靠性。最后介绍了下沉庭院大跨度无柱弧形楼梯的设计,并对其进行舒适度验算,结果满足规范要求。

基于激光雷达的多层楼梯检测和建模方法

移动机器人在多层建筑进行自主导航时,需要具备楼梯检测和建模能力。然而,目前楼梯检测和建模主要面向单层直楼梯,对具有回转结构的多层楼梯适用性差,且场景中存在的动态点云会影响建模精度。针对以上问题,提出了一种基于激光雷达的多层楼梯检测和建模方法。首先,构建了轻量化的2.5D点云滤波器,高效滤除动态和噪声点云;其次,提出了一种基于主成分分析的台阶分类方法,实现了对单个及具有回转结构的复杂多层楼梯的鲁棒台阶检测;同时,设计了一种基于区域分割的台阶尺寸估计方法,提高了楼梯模型的构建精度;此外,提出了一种基于多阈值判断的楼梯模型追踪方法,实现了实时楼梯检测和快速动态建模;最后,分别使用Tang数据集和四足机器人在室内外多重场景下采集的点云数据进行试验验证。结果表明,提出的算法在室内外场景下,能够对单层及具有回转结构的多层楼梯进行动态检测和建模,其中台阶尺寸的估计精度在1 cm以内,计算量降低了51.23%。

考虑洪水入侵的地铁站楼梯疏散风险研究

为增强地铁站应对洪涝灾害能力和楼梯设计韧性,基于改进的k-ε模型和洪涝疏散风险评价模型,构建地铁站楼梯上洪水入侵流态数值仿真场景,定量分析坡梯设置、楼梯倾斜度和洪水深度对洪涝疏散风险的影响。研究结果表明:在相同倾斜度(23.2°)和入侵洪水水深(0.3 m)的情况下,相较于楼梯台阶对洪水的阻缓作用,斜坡上洪水流速更快、水深更为平稳,但斜坡具有更高的洪涝疏散风险;洪涝疏散风险与楼梯倾斜度成正相关,疏散风险随着楼梯台阶的降低呈现“前快后缓”特征,斜坡对疏散风险的边际影响更为均匀,而宽大的台阶设置更有利于缓解疏散风险;楼梯上平台入口水深越大,洪涝疏散风险越高;洪水与下平台积水容易产生跳水现象,导致洪涝疏散风险急剧攀升和震荡递减。研究结果可为地铁站科学制定洪涝疏散方案和楼梯设计提供理论指导和管理启示。

一种鲁棒区分PJVS交流量子电压台阶平稳区与过渡区的判据

可编程约瑟夫森电压基准(programmable Josephson voltage standard,PJVS)通过生成阶梯波构建交流量子电压,其产生量子电压台阶过程中,会伴生过渡过程,导致电压台阶两端数据的准确性较低。常见的数据处理方法是将过渡过程的数据剔除,仅利用量子电压台阶上平稳区的数据,实现交流量子电压量值的复现。针对常用的3σ(σ为数据标准差)准则、片段采样方法等数据筛选准则,该文提出一种由量子电压台阶中心双向延拓并最小化A类测量不确定度的平稳区与过渡区判据,通过自动识别量子电压台阶的平稳区与过渡区,提升PJVS电压阶梯波复现交流电压量值的准确性。实验结果表明:该文提出的数据平稳区与过渡区的判据具有较高的鲁棒性和交流电压复现准确性,在2.5 kHz范围内,可使量子电压阶梯波信号复现交流电压幅值的偏差和A类测量不确定度均优于2.5×10-6。研究成果可有效提升量子电压阶梯波信号的测算准确性。

西北冰洋大西洋水与太平洋冬季水在波弗特流涡变化背景下的调整与响应

大西洋水是北冰洋内部最重要的储热层,而西北冰洋楚科奇边陲区域是大西洋水进入加拿大海盆的关键海域,研究大西洋水在楚科奇边陲区域的变化能深入揭示大西洋水对北冰洋的影响。本文收集整理并校正1999-2021年的大量历史水文数据,探讨了近年来在波弗特流涡加强和摆动背景下,大西洋水、太平洋冬季水和双扩散阶梯结构在西北冰洋楚科奇边陲区域的时空变化。结果表明,在研究时段内楚科奇边陲区域出现了3次大西洋水暖异常信号,出现时间分别在2000年、 2012年和2018年,异常暖水核心处的位温均超过1℃。太平洋冬季水核心和大西洋水核心间垂向平均热含量在楚科奇边陲区域中部和东部显著升高,主要归因于太平洋冬季水核心位温的增高。太平洋冬季水核心深度对波弗特流涡变化的响应相比大西洋水更显著。太平洋冬季水核心位温与大西洋水核心位温的联动变化调制着双扩散阶梯结构的变化。加拿大海盆内的双扩散阶梯结构呈现出从大阶梯结构向小阶梯结构过渡、直至大范围消亡的演变。该过程的主要调控机制为大西洋水核心位温的降低以及其上界面层化的增强抑制了垂向混合。

面向动目标围捕的Multi-UUV编队协调控制研究

针对动目标围捕过程对Multi-UUV编队结构的灵活性要求较高的问题,基于欠驱动UUV的数学模型,在目标轨迹能够准确预测的前提下,改进了协调编队运动控制器。协调编队运动控制器的控制目标是在Multi-UUV编队跟踪并围捕动目标过程中,避免Multi-UUV之间,UUV与障碍物以及UUV与动目标之间的碰撞并以稳定的编队结构围捕动目标。将控制器设计过程分解为运动学控制和动力学控制。在运动学控制部分,实现动目标跟踪、UUV之间避撞及UUV偏航角误差为零的控制目标。在动力学控制部分,应用反步法设计实际的控制输入。仿真案例验证了协调运动控制器在动目标围捕中的有效性。

基于Pyrosim的楼梯间火灾烟气数值模拟与分析

为分析老旧高层住宅楼在火灾场景下烟气的发展过程,以某高层住宅建筑为研究背景,通过Pyrosim软件建立火灾仿真模型,分析火灾场景下烟气在楼梯间的蔓延规律并通过开启不同楼梯间高度的窗户分析其对烟气排放的效果,对比不同楼梯间高度开窗烟气排放仿真模拟结果。结果发现:在烟气充满整个楼梯间的条件下,7层楼梯间开窗180 s时可达到3层楼梯间清晰;27层楼梯间开窗180 s时可达到6层楼梯间清晰;7层和27层楼梯间同时开窗180 s时可达到7层楼梯间清晰;在楼梯间最高处开窗180 s时可达到8层楼梯间清晰。综合楼梯间开窗排烟效果可知,楼梯间最高处开窗>中和面上、下同时开窗>中和面以上开窗>中和面以下开窗。

面向直流微电网的混合级联多电平逆变器阶梯波控制策略研究

级联多电平变换器将数个全桥逆变模块以级联方式进行连接并予以控制,适用于中压大功率输出场景下的直流微电网,广泛应用于能量路由器、智能电能网关、固态变压器等电力电子装置中.传统级联多电平变换器所级联的每一路逆变模块的电压相同,限制了多电平输出电压的电平数量.为解决上述问题,将传统的母线电压相等的三路级联7电平逆变器改造成母线电压为2的倍数关系(20∶21∶22)的三路混合级联15电平逆变器,通过采用阶梯波控制方法,并针对最近电平逼近法进行了改良以产生开关器件的触发信号,可有效降低开关器件的开关频率和开关损耗,并将输出电压由7电平增加到15电平,有效降低谐波.从混合级联15电平逆变器工作原理、阶梯波调制方法、输出电压谐波等角度开展了理论分析与计算,最终搭建样机进行实验,有效验证了所提出的分析和研究.

地下工程U形阶梯洪水入侵流场的三维数值模拟

为研究地下工程U形阶梯在洪水入侵灾害工况下的流场特性,利用三维计算流体力学(CFD)以及VOF多相流模型,对不同进水水深、进水流速以及进水位置工况下阶梯通道内的流场特性进行了三维流场数值模拟。结果表明:洪水从阶梯通道上方进口流入后,会在阶梯靠近栏杆处形成低速区,人员可经此低速区逃生;合理地设计阶梯通道的进门位置,有利于通道内侧低速区的形成;相较于进口流速,进口水深对阶梯上水深与流速的影响最为明显,进口水深越低,阶梯上水深与流速越低,越利于人员逃生。

基于YOLOv5s楼梯图像检测识别方法研究

楼梯区域作为一种典型的环境目标,无论是可以自主爬楼梯的机器人系统,还是可以提醒视力障碍者注意障碍物的软件系统,都需要有检测识别楼梯的功能。为了帮助他们在周围环境中导航,设计了一种基于YOLOv5s的楼梯图像检测算法。首先采用Labelme对楼梯数据集进行图片标注,对标注文件进行格式转化;其次搭建YOLOv5s网络模型训练环境,修改预训练模型配置文件,然后启动模型权重数据迁移训练,并输出最优模型参数;最后加载测试数据集对训练最优模型算法进行效果测试,算法均能识别出上下楼梯图像,并通过与其他目标检测算法对比测试,其具有更高的识别准确率。结果表明,该算法检测平均精度达到80.3%,泛化能力强,将该算法用于上下楼梯区域检测方法是可行的,可以为机器人对楼梯的自动检测识别提供一些参考,也可以为视障者提供有效帮助,市场应用前景良好。