Simultaneous pole-placement/stabilization of pairs of linear time-invariant plants using a continuous-time periodic controller

Given a pair of single input single output (SISO), linear time-invariant (LTI), and strictly proper plants of relative order r, this paper employs a continuous-time periodic controller to achieve 1) simultaneous pole-placement for r = 1 and 2) guaranteed simultaneous stabilization for r = 2; 3, and 4, which jobs LTI controllers cannot, in general, do. The controller also ensures insignificant output ripples. The analysis is based on averaging principle. The computational steps for controller synthesis are linear algebraic in nature. An example illustrates the design procedure.     

Micropyretic Synthesis of Refractory Metal Intermetallic Compounds

Abstract

The processing of refractory metal intermetallic compounds by micropyretic synthesis has been discussed in this article. The advantages of this process have been elaborated with the synthesis of intermetallic compounds in view. Microstructures of the synthesized alloys have been examined in detail and compared with the conventionally produced microstructure. The effect of different process parameters on the process and on the synthesized microstructure has been described. Special emphasis is given on the synthesis of aluminides of Nb and Ti and NiTi. The mechanism of micropyretic synthesis of the aforementioned intermetallic compounds from elemental powders has been studied by arresting the synthesis process midway. This has resulted in preservation of the unsynthesized material on one side, the fully synthesized material on the other and intermediate stages of synthesis frozen in between. A detailed microstructural characterization has been carried out around the arrested synthesis front in order to establish the sequence of synthesis.     

印度东部钛磁铁矿的氧化行为和相分析

钛磁铁矿是一种复杂的共生矿石,含有钛铁矿、磁铁矿、铁铝尖晶石和镁铁铝尖晶石等矿物。对从印度东部采集到的钛磁铁矿石进行XRD、WDXRF、SEM和M？ssbauer谱分析。在氧气气氛下,通过TG-DTA分析对矿石的氧化行为进行研究。随后,在氧气和空气气氛下,将样品在不同温度下（873-1473 K）保温不同时间,进行等温氧化实验。观察到在较低的温度下钛铁矿相转变为赤铁矿、氧化钛,而在较高的温度下转变为钛酸亚铁相。将氧化后的矿样与焦炭混合压制成圆柱形球团,在1473 K下进行直接还原,成功地实现了将磁铁矿铁转变为氧化铁和二氧化钛的相变。     

Optimum lateral extent of soil domain for dynamic SSI analysis of RC framed buildings on pile foundations

This article describes a novel approach for deciding optimal horizontal extent of soil domain to be used for finite element based numerical dynamic soil structure interaction (SSI) studies. SSI model for a 12 storied building frame, supported on pile foundation-soil system, is developed in the finite element based software framework, OpenSEES. Three different structure-foundation configurations are analyzed under different ground motion characteristics. Lateral extent of soil domain, along with the soil properties, were varied exhaustively for a particular structural configuration. Based on the reduction in the variation of acceleration response at different locations in the SSI system (quantified by normalized root mean square error, NRMSE), the optimum lateral extent of the soil domain is prescribed for various structural widths, soil types and peak ground acceleration levels of ground motion. Compared to the past studies, error estimation analysis shows that the relationships prescribed in the present study are credible and more inclusive of the various factors that influence SSI. These relationships can be readily applied for deciding upon the lateral extent of the soil domain for conducting precise SSI analysis with reduced computational time.     

Is Someone in this Office Available to Help Me?

Robots are increasingly autonomous in our environments, but they still must overcome limited sensing, reasoning, and actuating capabilities while completing services for humans. While some work has focused on robots that proactively request help from humans to reduce their limitations, the work often assumes that humans are supervising the robot and always available to help. In this work, we instead investigate the feasibility of asking for help from humans in the environment who benefit from its services. Unlike other human helpers that constantly monitor a robot’s progress, humans in the environment are not supervisors and a robot must proactively navigate to them to receive help. We contribute a study that shows that several of our environment occupants are willing to help our robot, but, as expected, they have constraints that limit their availability due to their own work schedules. Interestingly, the study further shows that an available human is not always in close proximity to the robot. We present an extended model that includes the availability of humans in the environment, and demonstrate how a navigation planner can incorporate this information to plan paths that increase the likelihood that a robot can find an available helper when it needs one. Finally, we discuss further opportunities for the robot to adapt and learn from the occupants over time.     

Perovskite solar cells: recent progress and strategies developed for minimizing interfacial recombination

Organometallic perovskite is a new generation photovoltaic material with exemplary properties such as high absorption co-efficient, optimal bandgap, high defect tolerance factor and long carrier diffusion length. However, suitable electrodes and charge transport materials are required to fulfill photovoltaic processes where interfaces between hole transport material/perovskite and perovskite/electron transport material are affected by phenomena of charge carrier separation, transportation, collection by the interfaces and band alignment. Based on recent available literature and several strategies for minimizing the recombination of charge carriers at the interfaces, this review addresses the properties of hole transport materials, relevant working mechanisms, and the interface engineering of perovskite solar cell (PSC) device architecture, which also provides significant insights to design and development of PSC devices with high efficiency.     

Studies on the interaction of ‐epigallocatechin‐3‐gallate from green tea with bovine β‐lactoglobulin by spectroscopic methods and docking

The binding interaction between‐epigallocatechin‐3‐gallate (EGCG) and bovine β‐lactoglobulin (βLG) was thoroughly studied by fluorescence, circular dichroism (CD) and protein–ligand docking. Fluorescence data revealed that the fluorescence quenching of βLG by EGCG was the result of the formation of a complex of βLG–EGCG. The binding constants and thermodynamic parameters at two different temperatures and the binding force were determined. The binding interaction between EGCG and βLG was mainly hydrophobic and the complex was stabilised by hydrogen bonding. The results suggested that βLG in complex with EGCG changes its native conformation. Furthermore, preheat treatment (90 °C, 120 °C) and emulsifier (sucrose fatty acid ester) all boosted the binding constants (K_a) and the binding site values (n) of the βLG‐EGCG complex. This study provided important insight into the mechanism of binding interactions of green tea flavonoids with milk protein.     

Algorithmic approaches for optimizing electronic control unit time using multi-rate sampling

With the emerging migration of automotive and other distributed control platforms from federated to integrated architectures, the need for optimal utilization of ECU (electronic control unit) bandwidth will become a key requirement in the implementation of embedded control features. This paper advocates the partitioning of the operating space of the plant and the use of minimal sampling rates in each partition without compromising the overall quality of control. At the heart of the proposed methodology are our algorithms that enable the choice of the partitions and the sampling rate for each partition. We demonstrate the efficacy of our methods on two case studies, namely an anti-lock braking system and a lane departure warning system. We also study the use of a supervisory controller that controls the switching among sampling rates for a combination of the two features.     

Location-Based Services

Today, location information is in the hands of the masses. The success of location in pervasive computing has exposed new challenges and opportunities for researchers including making location sensing more robust, accurate, deployable, secure, and developer-friendly. This special issue showcases papers that describe recent research that addresses these challenges.