Enhanced UV- and visible-light driven photocatalytic performances and recycling properties of graphene oxide/ZnO hybrid layers

Light induced catalytic processes have attracted significant attention during the last years for wastewater treatment due to their efficiency in decomposition of organic contaminants. In this study we report the synthesis of graphene oxide (GO)/ZnO hybrid layers with high photocatalytic efficiency using laser radiation. The results show that the hybrid layers exhibit much improved photodecomposition efficiency as compared to pure GO or ZnO both under UV and visible-light irradiation. The enhanced photocatalytic efficiency of the hybrid as compared to the reference pure ZnO and GO layers was attributed to the contribution of GO to the separation and transport of the photogenerated charge carriers. Additionally, under visible light irradiation the organic molecules can act as first sensitizers in the degradation process. The recyclability of the layers was also investigated through repetitive photodegradation cycles under UV- or visible-light irradiation. After consecutive degradation runs, the hybrid photocatalyst layers were still stable and retained high degradation efficiency, ensuring reusability. The photocatalytic activity of the layers was correlated with the gradual change of their chemical structure during consecutive degradation cycles. Owing to the high photodegradation efficiency, reusability, and ease of recovery the synthesised hybrid layers consisting of easily available materials are suitable for environmental purification applications.     

Abstractions of data types

The use of abstraction in the context of abstract data types, is investigated. Properties to be checked are formulas in a first order logic under Kleene's 3-valued interpretation. Abstractions are defined as pairs consisting of a congruence and a predicate interpretation. Three types of abstractions are considered,∀∀, ∀∃ and ∃^0,1∀, and for each of them corresponding property preservation results are established. An abstraction refinement property is also obtained. It shows how one can pass from an existing abstraction to a (less) finer one. Finally, equationally specified abstractions in the context of equationally specified abstract data types are discussed and exemplified.On leave from the Department of Computer Science, “Al. I. Cuza” University, Iaşi 740083, RomaniaThe research reported in this paper was partially supported by the program ECO-NET 08112WJ/2004-2005 and by the National University Research Council of Romania, grants CNCSIS 632(28)/2004 and CNCSIS 632(50)/2005.     

Process and learning outcomes from remotely-operated,simulated, and hands-on student laboratories

A large-scale, multi-year, randomized study compared learning activities and outcomes for hands-on, remotely-operated, and simulation-based educational laboratories in an undergraduate engineering course. Students (N = 458) worked in small-group lab teams to perform two experiments involving stress on a cantilever beam. Each team conducted the experiments in one of three lab formats (hands-on, remotely-operated, or simulation-based), collecting data either individually or as a team. Lab format and data-collection mode showed an interaction, such that for the hands-on lab format learning outcomes were higher when the lab team collected data sets working as a group rather than individually collecting data sets to be combined later, while for remotely-operated labs individual data collection was best. The pattern of time spent on various lab-related activities suggests that working with real instead of simulated data may induce higher levels of motivation. The results also suggest that learning with computer-mediated technologies can be improved by careful design and coordination of group and individual activities.     

Profiling the operational behavior of OS device drivers

As the complexity of modern Operating Systems (OS) increases, testing key OS components such as device drivers (DD) becomes increasingly complex given the multitude of possible DD interactions. Currently, DD testing entails a broad spectrum of techniques, where static (requiring source code) and dynamic (requiring the executable image) and static-dynamic testing combinations are employed. Despite the sustained and improving test efforts in the field of driver development, DDs still represent a significant cause of system outages as the coverage is invariably limited by test resources and release time considerations. The basic factor is the inability to exhaustively assess and then cover the operational states, leading to releases of inadequately tested DDs. Consequently, if representative operational activity profiles of DDs within an OS could be obtained, these could significantly improve the understanding of the actual operational DD state space and help focus the test efforts. Focusing on characterizing DD operational activities while assuming no access to source code, this paper proposes a quantitative technique for profiling the runtime behavior of DDs using a set of occurrence and temporal metrics obtained via I/O traffic characterization. Such profiles are used to improve test adequacy against real-world workloads by enabling similarity quantification across them. The profiles also reveal execution hotspots in terms of DD functionalities activated in the field, thus allowing for dedicated test campaigns. A case study on actual Windows XP and Vista drivers using various performance and stability benchmarks as workloads substantiates our proposed approach.     

Plate tectonic reconstructions with continuously closing plates

We present a new algorithm for modeling a self-consistent set of global plate polygons. Each plate polygon is composed of a finite list of plate margins, all with different Euler poles. We introduce a "continuously closed plate" (CCP), such that, as each margin moves independently, the plate polygon remains closed geometrically as a function of time. This method solves emerging needs in computational geodynamics to combine kinematic with dynamic models. Because they have polygons that are too widely spaced in time and have inconsistent motions between margins and plates, traditional global plate tectonic reconstructions have become inadequate for geodynamics. The CCP algorithm has been incorporated into the GPlates open-source paleogeographic system. The algorithm is a set of procedures and data structures that operate on collections of reconstructed geometric data to form closed plate polygons; the main data structures used for each plate polygon are based on a nested hierarchy of topological elements. Reconstructions with CCPs can be created, edited, visualized, and exported with GPlates. The native storage of the dynamic reconstructions is the GPlates Markup Language, GPML, which uses an XML-based file format called GML. We demonstrate the utility of the CCP method by creating a global reconstruction with continuously closing plates from 140 Ma to the present using data from existing, traditional reconstructions.     

Observer-based predictive controller design with network-enhanced time-delay compensation

State feedback control is very attractive due to the precise computation of the gain matrix, but the implementation of a state feedback controller is possible only when all state variables are directly measurable. This condition is almost impossible to accomplish due to the excess number of required sensors or unavailability of states for measurement in most of the practical situations. Hence, the need for an estimator or observer is obvious to estimate all the state variables by observing the input and the output of the controlled system. As such, the goal of this paper is to provide a control design methodology based on a Luenberger observer design that can assure the closed-loop performances of a vehicle drivetrain with backlash, while compensating the network-enhanced time-varying delays. This goal is achieved in a sequential manner: firstly, a piecewise linear model of two inertias drivetrain, which takes into consideration the backlash nonlinearity and the network-enhanced time-varying delay effects is derived; then, a Luenberger observer which estimates the state variables is synthesized and the robust full state-feedback predictive controller based on flexible control Lyapunov functions is designed to explicitly take into account the bounds of the disturbances caused by time-varying delays and to guarantee also the input-to-state stability of the system in a non-conservative way. The full state-feedback predictive control strategy based on the Luenberger observer design was experimentally tested on a vehicle drivetrain emulator controlled through controller area network, with the aim of minimizing the backlash effects while compensating the network-enhanced delays.     

Lyapunov based predictive control of vehicle drivetrains over CAN

Vehicle drivetrains are characterized by fast dynamics, subject to physical and control constraints, which make controller design for driveline oscillations damping a challenging problem. Furthermore, in current implementations, the connections between the controller and the physical plant are realized using a controller area network (CAN) as the communication medium, which introduces time-varying delays. As such, the goal of this paper is to provide a control design methodology that can cope with all these challenges and limitations and still yield an effective solution. To this end, firstly, a continuous-time model of a vehicle drivetrain is derived. Then, a method for determining a worst case upper bound on the delays that can be introduced by a CAN is presented, which enables the usage of a polytopic approximation technique to obtain a discrete-time model of the closed-loop CAN system. Thirdly, a non-conservative Lyapunov based predictive controller is designed for the resulting model with time-varying delays, polytopic uncertainty and hard constraints. Several tests performed using an industry validated drivetrain model and the Matlab toolbox TrueTime indicate that the proposed design methodology can handle both the performance/physical constraints and the strict limitations on the computational complexity, while effectively coping with time-varying delays. Preliminary real-time results further validate the proposed methodology.     

Visual Interestingness Prediction: A Benchmark Framework and Literature Review

International Journal of Computer Vision - In this paper, we report on the creation of a publicly available, common evaluation framework for image and video visual interestingness prediction. We...     

On the connection between the exponential stability of C0-semigroups and the admissibility of a certain Sobolev space

Let T be a strongly continuous semigroup on a Banach space X and A its infinitesimal generator. We will prove that T is exponentially stable, if and only if, there exist p[1,∞) such that the space is admissible to the system Σ(A,I,I), defined below (i.e for all f belonging to the Sobolev space the convolution T*f lies in .     

Can newborns discriminate between their own cry and the cry of another newborn infant?

Two experiments were conducted to test whether newborns could discriminate between their own cry and the cry of another newborn infant. Facial behavior and nonnutritive sucking rate were adopted as dependent measures. In Experiment 1, 20 newborns in an awake state were presented with either their own cry or the cry of another infant. In the latter condition, newborns showed the facial expression of distress more frequently and for a longer duration. In addition, the rate of sucking decreased significantly between the pretest phase and the 1st min of presentation of another infant's cry. Newborns' responses, although delayed and less intense, showed a similar trend in Experiment 2, during which 20 newborns in a sleep state were tested with the same procedure. These results indicate the newborns' capability to discriminate between the 2 cry stimuli and show the effectiveness of a newborn cry in inducing distress signals in another newborn infant. (PsycINFO Database Record (c) 2010 APA, all rights reserved)