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.

Observational analysis of the double-diffusive convection in the deep Canada Basin

The Canada Basin （CB） is the largest sub-basin in the Arctic, with the deepest abyssal plain of 3 850 m. The double-diffusive process is the possible passage through which the geothermal energy affects the above isolated deep waters. With the temperature-salinity-pressure observations in 2003, 500-m-thick transition layers and lower 1 000-m-thick bottom homogenous layers were found below 2 400 m in the central deep CB. Staircases with downward-increasing temperature and salinity are prominent in the transition layers, suggesting the double- diffusive convection in deep CB. The interface of the stairs is about 10 m thick with 0.001-0.002℃ temperature difference, while the thicknesses of the homogenous layers in the steps decrease upward from about 60 to 20 m. The density ratio in the deep central CB is generally smaller than 2, indicating stronger double-diffusive convection than that in the upper ocean of 200-400 m. The heat flux through the deepest staircases in the deep CB varies between 0.014 and 0.031 W/m2, which is one-two orders smaller than the upper double-diffusive heat flux, but comparable to the estimates of geothermal heat flux.

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.

Cross-diffusive effects on the onset of double-diffusive convection in a horizontal saturated porous fluid layer heated and salted from above

Double-diffusive stationary and oscillatory instabilities at the marginal state in a saturated porous horizontal fluid layer heated and salted from above are investigated theoretically under the Darcy＇s framework for a porous medium. The contributions of Soret and Dufour coefficients are taken into account in the analysis. Linear stability analysis shows that the critical value of the Darcy-Rayleigh number depends on cross-diffusive parameters at marginally stationary convec- tion, while the marginal state characterized by oscillatory convection does not depend on the cross-diffusion terms even if the condition and frequency of oscillatory convection depends on the cross-diffusive parameters. The critical value of the Darcy-Rayleigh number increases with increasing value of the solutal Darcy-Rayleigh number in the absence of cross- diffusive parameters. The critical Darcy-Rayleigh number decreases with increasing Soret number, resulting in destabiliza- tion of the system, while its value increases with increasing Dufour number, resulting in stabilization of the system at the marginal state characterized by stationary convection. The analysis reveals that the Dufour and Soret parameters as well as the porosity parameter play an important role in deciding the type of instability at the onset. This analysis also indicates that the stationary convection is followed by the oscillatory convection for certain fluid mixtures. It is interesting to note that the roles of cross-diffusive parameters on the double-diffusive system heated and salted from above are reciprocal to the double-diffusive system heated and salted from below.

Conceptual Analysis of a Time-Dependent Double-Diffusive Flow over a Semi-Infinite Vertical Plate

This study is devoted to the analysis of a one-dimensional time-dependent double-diffusive flow over a semi-infinite vertical plate, under a convective surface boundary condition. Using similarity variable, the governing nonlinear partial differential equations have been transformed into a set of coupled nonlinear ordinary differential equations, which are solved numerically by using shooting method alongside with Runge-Kutta integration scheme as embedded in Maple software programme. The numerical results of the skin-friction coefficient, the Nusselt and Sherwood numbers are discussed and depicted graphically.

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.

Visualization of Double-Diffusive Convection and Unsteady Solidification on a Vertical Circular Cylinder

This paper describes experimental results on the solidification process over the vertically positioned circular cylinder, placed in an aqueous solution of sodium nitrate, where the aqueous solution in the vessel is heated from the bottom. After the initiation of solidification by cooling the cylinder below the liquidus temperature, the pure ice formation on the cylinder causes the rejection of solute into the surrounding aqueous solution. The solute enriched vertical fluid layer over the ice then falls on the bottom of the vessel due to its higher density, and accumulates there. This process results in the formation of solute rich and hot horizontal layer (heavy layer), underlying the relatively cold but less concentrated fluid layer (light layer). As this process advances, however, because of the continuing influx of solute rich fluid, the lower heavy layer occupies more space, and the interface of the two layers rises slowly. The pH indicator method has been successfully employed in order to visualize the flows during this process. In this report, we document the evolution of both temperature and flow fields in the aqueous solution quantitatively, as the solidification progresses and the density discontinuity of the two layers rises.

Plane Stagnation Double-Diffusive MHD Convective Flow with Convective Boundary Condition in a Porous Media

A numerical analysis has been carried out to study the problem of plane stagnation double-diffusive MHD convective flow with convective boundary condition in a porous media. The governing nonlinear partial differential equations have been reduced to systems of nonlinear ordinary differential equations by the similarity transformations. The transformed equations are solved numerically by using the classical fourth order Runge-Kutta method together with the shooting technique implemented on a computer program. The effects of the physical parameters are examined on the velocity, temperature and concentration profiles. Numerical data for the skin-friction coefficients, Nusselt and Sherwood numbers have been tabulated for various parametric conditions and are also shown graphically and discussed.

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。

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。