On the performance of improved quadrature spatial modulation

Quadrature spatial modulation (QSM) utilizes the in‐phase and quadrature spatial dimensions to transmit the real and imaginary parts of a single signal symbol, respectively. The improved QSM (IQSM) transmits two signal symbols per channel use through a combination of two antennas for each of the real and imaginary parts. The main contributions of this study can be summarized as follows. First, we derive an upper bound for the error performance of the IQSM. We then design constellation sets that minimize the error performance of the IQSM for several system configurations. Second, we propose a double QSM (DQSM) that transmits the real and imaginary parts of two signal symbols through any available transmit antennas. Finally, we propose a parallel IQSM (PIQSM) that splits the antenna set into equal subsets and performs IQSM within each subset using the same two signal symbols. Simulation results demonstrate that the proposed constellations significantly outperform conventional constellations. Additionally, DQSM and PIQSM provide a performance similar to that of IQSM while requiring a smaller number of transmit antennas and outperform IQSM with the same number of transmit antennas.     

Porous ceramics with tailored pore size and morphology as substrates for coral larval settlement

The growing demand for stony corals as ornamental aquarium animals requires defined aquacultural breeding strategies. For the sexual propagation of corals, material substrates are needed, that attract larvae and support their settlement and development. In this study, five types of highly porous ceramic materials were developed following the example of coral skeleton. The applicability of these settlement substrates was tested using larvae of the stony coral Pocillopora damicornis. Partial sintering of pressed clay pellets, freeze casting of clay and alumina-mullite based slurries and direct foaming of high alkane phase emulsified suspensions (HAPES) using alumina were employed. By the addition of mm-sized spherical polystyrene beads as sacrificial templates during freeze casting (alumina-mullite), superficial pores in the size of the larvae were created. The inorganic substrates featured open porosities between 35% (pressed clay) and 83% (foamed alumina), pore sizes ranging from nm to mm-scale and pore morphologies dominated by interparticle porosity (pressed), lamellar pores (freeze casting) and cellular pore types (direct foaming). The ceramic substrates were incubated in artificial sea water for 3 months to induce necessary biofilm formation and algae growth. Afterwards, individual substrates were exposed to 5 coral larvae, and their settlement behavior was monitored over 14 days. At the end of this period, all ceramic materials were successfully accepted as settlement substrates, with a mean settlement rate of 46.2%, and no significant differences between the substrate types. On samples with large surface superficial pores, a significantly reduced survival of settled larvae (79%) compared to the other porous materials (93–98%) was determined, suggesting a non-ideal surface topography. While alumina foam samples (HAPES) exhibit the most promising results in terms of settlement and survival of larvae, clay-based substrates provide a more economic solution for the sexual propagation of corals in aquaculture.     

Group sequential crossover trial designs with strong control of the familywise error rate

Crossover designs are an extremely useful tool to investigators, and group sequential methods have proven highly proficient at improving the efficiency of parallel group trials. Yet, group sequential methods and crossover designs have rarely been paired together. One possible explanation for this could be the absence of a formal proof of how to strongly control the familywise error rate in the case when multiple comparisons will be made. Here, we provide this proof, valid for any number of initial experimental treatments and any number of stages, when results are analyzed using a linear mixed model. We then establish formulae for the expected sample size and expected number of observations of such a trial, given any choice of stopping boundaries. Finally, utilizing the four-treatment, four-period TOMADO trial as an example, we demonstrate that group sequential methods in this setting could have reduced the trials expected number of observations under the global null hypothesis by over 33%.     

云冈矿8602工作面进回风巷贯通测量的研究

综合机械化掘进工艺工作面走向越长,贯通距离越长,误差积累越大。以云冈矿8602工作面进回风巷道为例,提出了降低贯通测量误差的技术措施,实践结果表明贯通巷道偏差符合要求,贯通闭合实测误差符合设计要求。     

原始钻孔轨迹模型的建立及模拟方法的精度对比

建立原始钻孔轨迹模型,可以为各种轨迹模拟方法计算精度分析及误差因素量化分析提供数据基础。测点要素间的关系可以看作顶角、方位关于深度的函数关系,将这种函数关系模型化,可获得模型曲线的切向量关于深度的函数关系。以此为基础,用微分方法得到曲线三维坐标关于深度的导函数,再用积分方法即可得到原始钻孔轨迹模型曲线。该模型提供了不同弯曲强度条件下的原始钻孔测点要素和三维坐标,对全角半距法和最小曲率法2种模拟方法进行误差计算、对比和分析,验证了在计算精度上最小曲率法优于全角半距法。根据计算结果得出了2种方法在计算误差上的差异,并针对勘查钻孔和定向钻孔2种实际应用条件得出相应的计算精度。     

A Global Maximum Error Controller Based Nonlinearity Aware TPWL Method for Reducing Nonlinear Systems

Abstract

Model order reduction is a common practice to reduce large order systems so that their simulation and control become easy. Nonlinearity aware trajectory piecewise linear is a variation of trajectory piecewise linearization technique of order reduction that is used to reduce nonlinear systems. With this scheme, the reduced approximation of the system is generated by weighted sum of the linearized and reduced sub-models obtained at certain linearization points on the system trajectory. This scheme uses dynamically inspired weight assignment that makes the approximation nonlinearity aware. Just as weight assignment, the process of linearization points selection is also important for generating faithful approximations. This article uses a global maximum error controller based linearization points selection scheme according to which a state is chosen as a linearization point if the error between a current reduced model and the full order nonlinear system reaches a maximum value. A combination that not only selects linearization points based on an error controller but also assigns dynamic inspired weights is shown in this article. The proposed scheme generates approximations with higher accuracies. This is demonstrated by applying the proposed method to some benchmark nonlinear circuits including RC ladder network and inverter chain circuit and comparing the results with the conventional schemes.     

自动电位滴定仪示值误差测量不确定度评定

按照JJG 814-2015规定,自动电位滴定仪需进行电计示值误差和仪器示值误差检定,本文例举对这两项检定结果进行不确定度评定,供相关人员参考。     

动圈仪表的温度附加误差及其补偿方法

本文对动圈仪表产生温度附加误差的各种因素作了一定的理论分析,并提出了相应的补偿措施。文章以多幅图、表及实例作了论述。     

由工程施工导致的自动化仪表失准案例分析

本文针对案例进行分析,提出一些刚投入使用的自动化仪表出现不合格现象,而这些不合格的原因不是出厂时就存在的,而是由于自动化仪表安装人员在安装过程中没有严格执行自动化仪表工程施工及质量验收规范和相应产品使用说明书的要求所导致的,是完全可以避免的。     

尘埃粒子计数器校准结果及其应用探讨

本文对尘埃粒子计数器粒子浓度示值误差校准结果的计算进行了讨论,并以制药行业中尘埃粒子计数器的使用为例对尘埃粒子计数器校准结果的应用进行了探讨。