Stationary policies for lower bounds on the minimum average cost of discrete‐time nonlinear control systems

The paper deals with the control problem of discrete‐time nonlinear systems. The main contribution of this note is to present conditions that assure the existence of stationary policies that generate lower bounds for the minimal long‐run average cost. These lower bounds coincide with the optimal solution when a mild convergence assumption holds. To illustrate the results, the paper presents an application for the simultaneous state‐feedback control problem, and the derived strategy is used to design a real‐time simultaneous control for two direct current motor devices. The dynamics of these two devices are written in terms of a nonlinear algebraic matrix recurrence, which in turn represents a particular case for our general nonlinear approach. The optimal gain for the corresponding simultaneous state‐feedback problem is obtained, and such a gain was implemented in a laboratory testbed to control simultaneously the two direct current motors. Copyright © 2013 John Wiley & Sons, Ltd.     

Rheological,thermal, and morphological properties of blends based on poly(propylene), ethylene propylene rubber,and ethylene-1-octene copolymer that could result from end of life vehicles: Effect of maleic anhydride grafted poly(propylene)

The objective of this work is to study the properties of blends that could result from the recycling of end-of-life vehicles (ELV). While ethylene propylene rubber (EPR) and ethylene propylene diene monomer (EPDM) have been used extensively as elastomeric additives in poly(propylene) (PP), they can be substituted by ethylene-1-octene copolymer (EOC). As a consequence, the matter resulting from the sorting of ELV might be more complex and made of PP, EPR, and EOC. The effect of incorporating EOC [that is a polyethylene elastomer (PEE)] and maleic anhydride grafted polypropylene (PP-g-MAH) on the rheological, thermal, and morphological properties of PP/EPR blends has been investigated. Blends of various compositions (with and without compatibilizer) were prepared using a corotating twin-screw extruder. The results were compared to the ones presented by a commercial (PP/EPR) blend. The EPR phase is dispersed in the form of spherical particles in (PP/EPR). The EOC phase is dispersed in the form of aggregated particles. Dynamic viscoelastic and differential scanning calorimetry properties of (PP/EPR)/EOC blends shows the incompatibility of the components even in presence of PP-g-MAH copolymer. POLYM. ENG. SCI., 47:1009–1015, 2007. © 2007 Society of Plastics Engineers     

Experimental methods in chemical engineering: X‐ray photoelectron spectroscopy‐XPS

X‐ray photoelectron spectroscopy (XPS) is a quantitative surface analysis technique used to identify the elemental composition, empirical formula, chemical state, and electronic state of an element. The kinetic energy of the electrons escaping from the material surface irradiated by an x‐ray beam produces a spectrum. XPS identifies chemical species and quantifies their content and the interactions between surface species. It is minimally destructive and is sensitive to a depth between 1–10nm. The elemental sensitivity is in the order of 0.1 atomic %. It requires ultra high vacuum ( Pa) in the analysis chamber and measurement time varies from minutes to hours per sample depending on the analyte. XPS dates back 50 years ago. New spectrometers, detectors, and variable size photon beams, reduce analysis time and increase spatial resolution. An XPS bibliometric map of the 10 000 articles indexed by Web of Science^[1] identifies five research clusters: (i) nanoparticles, thin films, and surfaces; (ii) catalysis, oxidation, reduction, stability, and oxides; (iii) nanocomposites, graphene, graphite, and electro‐chemistry; (iv) photocatalysis, water, visible light, and ; and (v) adsorption, aqueous solutions, and waste water.     

Patientenverfügung und Behandlungsvereinbarung als Instrumente der Vorausplanung in der forensischen Psychiatrie

Definition of the problem

In Germany as well as in many other countries, mentally ill criminals who are not guilty by reasons of insanity can be sentenced to psychiatric treatment in forensic clinics. In 2011, the German Constitutional Court substantially strengthened these patients’ right to self-determination in case of treatment refusal.

Arguments

In this context, we discuss the significance of instruments of advance healthcare planning. First, we describe the context of psychiatric treatment in forensic clinics and the changes the new German legal regulations brought about. A case study helps to illustrate the consequences of treatment refusal for both patient and healthcare personnel.

Conclusion

Eventually, we discuss if and how advance directives and joint crisis plans can be useful in forensic clinics and how additional measures can help to facilitate patient self-determination.

     

SDC-SCFZ dual-phase ceramics: Structure,electrical conductivity,thermal expansion,and O2 permeability

New CO₂-resistant dual-phase Sm_0.2Ce_0.8O_1.925–SrCo_0.4Fe_0.55Zr_0.05O_3-δ (SDC-SCFZ) ceramics present a promising outlook for potential future applications in membrane reactors and solid oxide fuel cells. Their high oxygen permeation flux and stability in CO₂ sweep gas also allow their integration in oxyfuel combustion. Here the structural characteristics, electrical conductivities, thermal expansion behaviors, and oxygen permeabilities of four different SDC-SCFZ membranes with weight ratios of 10:90, 25:75, 50:50, and 75:25 (SDC:SCFZ) are systematically studied. Among these four SDC-SCFZ compositions, 0.6 mm-thick 25 wt% SDC-75 wt% SCFZ displayed the highest oxygen permeation fluxes that reach 1.26 mL min⁻¹ cm⁻² at 950°C and retained its phase integrity under alternating He and CO₂ sweep gas over 72 hours of operation. This composite also showed a moderate thermal expansion coefficient of 1.90 × 10⁻⁵ K⁻¹ between 30°C and 1000°C and an electrical conductivity of at least 16 S cm⁻¹ at 550°C and above. Modeling studies revealed that the oxygen permeation fluxes through 25SDC-75SCFZ are limited by surface exchange reactions from 700°C to 800°C and mixed bulk diffusion and surface exchange reactions above 800°C.     

Synthesis method comparison of compositionally complex rare earth-based Ruddlesden–Popper n = 1 T′-type cuprates

The multicomponent approach has been successfully expanded to the Ruddlesden–Popper structure with the synthesis of two different high-entropy cuprate compositions: (La_0.2Nd_0.2Gd_0.2Tb_0.2Dy_0.2)₂CuO₄ and (La_0.2Pr_0.2Nd_0.2Sm_0.2Eu_0.2)₂CuO₄. The effect of synthesis method is explored using both solid-state reaction and polymeric steric entrapment (PSE) methods. It is found that PSE leads to more randomly distributed cation species, providing an advantageous method of synthesis for the growing field of high entropy oxides. In situ high-temperature x-ray diffraction tracks the amorphous to crystalline phase transformation in (La_0.2Nd_0.2Gd_0.2Tb_0.2Dy_0.2)₂CuO₄ powder, synthesized using the PSE method. Using the High-Temperature XRD data, a method for gaining information on the kinetic behavior is also applied. Magnetometry of both compositions indicates ferrimagnetic behavior at low temperatures.     

3D MRI of explanted sheep hearts with submillimeter isotropic spatial resolution: comparison between diffusion tensor and structure tensor imaging

Magnetic Resonance Materials in Physics, Biology and Medicine - The aim of the study is to compare structure tensor imaging (STI) with diffusion tensor imaging (DTI) of the sheep heart...     

Sustainable end-of-life vehicle recycling: R&;D collaboration between industry and the U.S. DOE

Approximately 15 million cars and trucks reach the end of their useful life in the United States each year. More than 75% of the materials from end-of-life vehicles are profitably recovered and recycled by the private sector; automotive materials recycling is a success story. To achieve greater fuel efficiency and safety, today’s cars incorporate an increasing share of innovative light-weight materials. While these materials greatly enhance efficiency during vehicle use, they can present special challenges for recycling. These challenges will persist as automotive designs and the mix of materials used in vehicles continue evolving to further improve safety and performance. To meet the challenges of automotive materials recycling, the U.S. Department of Energy has recently expanded its collaborative research with industry in this area. This article discusses this collaborative government/industry approach to sustainable end-of-life vehicle recycling. For more information, contact Edward J. Daniels, Argonne National Laboratory, 9700 S. Cass Avenue, Building 362, Room C393, Argonne, IL 60439-4815; (630) 252-5279; fax (630) 252-1342; e-mail edaniels@anl.gov.     

Output feedback of Markov jump linear systems with no mode observation: An automotive throttle application

The note presents an output feedback control strategy for Markov jump linear systems with no mode observation. Based on minimizing a finite‐time quadratic cost, we derive an algorithm that generates output feedback gains that satisfy a necessary optimality condition. These gains can be computed off‐line relying only on the initial condition of the system. This result expands a previous one from the literature that considered state‐feedback only. To illustrate the usefulness of the approach, real‐time laboratory experiments were performed to control an automotive electronic throttle valve subject to Markov‐driven voltage fluctuations. Copyright © 2015 John Wiley & Sons, Ltd.     

Exploring factors related to users’ experience of public transport route choice: influence of context and users profiles

This exploratory study aims to achieve a better understanding of the users-related factors that affect the choice of routes in public transport (PT). We also look at what can motivate route and modes changes towards alternatives in a real situation. We investigated the experience of 19 users of PTs, using the critical incident technique (Flanagan in Psychol Bull 51(4):327, 1954). We asked participants to report incidents (i.e. situations) in cases they were very satisfied or dissatisfied with their choice. For both situations, the case of their usual route and case of an alternative were considered. A total of 91 incidents were collected and analysed using a multiple correspondences analysis. Additionally, users’ profiles were characterized and superposed to the analysis of incidents content. The main results are as follows. First, the user’s choice of PT route depends on the context (i.e. aim of the travel, time of day). Second, taking an alternative to the usual PT route or using a route combining different transport modes is determined by the context and by factors related to the pleasantness of the travel (e.g. to accompany a friend along the travel). Finally, depending on the user’s profile (i.e. combination of attitude towards PT and demographic variables), the factors taken into account to make the choice of a PT route are related to the efficiency or the pleasantness of the trip. These results show the importance of the contextual factors and the users’ profiles in route choice. They suggest that these factors should be further taken into account in new tools and services for mobility.