1,881 research outputs found
Decimal to Binary Number Conversion can be Fun
Numbering systems are of great importance in Computer Science and Engineering education. The binary numbering system can be considered as one of the most fundamental, since its understanding is essential for the understanding of other Computer Science and Engineering concepts, such as data representation, data storage, computer architecture, networking, and many more. Yet, students are having difficulties understanding it. One approach which has been shown to improve learning of different science and mathematics concepts is the use of educational games. Educational games have the potential to engage and motivate learners through fun activities. This paper presents a small exploratory survey on an electronic educational game for practicing decimal to binary number conversions
The Gender Wage Gaps, 'Sticky Floors' and 'Glass Ceilings' of the European Union
We consider and attempt to understand the gender wage gap across 24 EU member states, all of which share the objective of gender equality, using 2007 data from the European Union Statistics on Income and Living Conditions. The size of the gender wage gap varies considerably across countries and selection corrections affect the offered gap, sometimes substantially. Most of the gap cannot be explained by the characteristics available in this data set. Quantile regressions show that, in most countries, the wage gap is wider at the top of the wage distribution ('glass ceilings') and, in fewer countries, it is wider at the bottom of the wage distribution ('sticky floors'). These features are related to country-specific characteristics that cannot be evaluated at the member state level. We use the cross-country variation in this large sample of member states to explore the influence of (i) policies concerned with reconciling work and family life and (ii) wage-setting institutions. We find that policies and institutions are systematically related to unexplained gender wage gaps.gender wage gap, selection, quantile effects, work-family reconciliation, wage-setting institutions
A distributed networked approach for fault detection of large-scale systems
Networked systems present some key new challenges in the development of fault diagnosis architectures. This paper proposes a novel distributed networked fault detection methodology for large-scale interconnected systems. The proposed formulation incorporates a synchronization methodology with a filtering approach in order to reduce the effect of measurement noise and time delays on the fault detection performance. The proposed approach allows the monitoring of multi-rate systems, where asynchronous and delayed measurements are available. This is achieved through the development of a virtual sensor scheme with a model-based re-synchronization algorithm and a delay compensation strategy for distributed fault diagnostic units. The monitoring architecture exploits an adaptive approximator with learning capabilities for handling uncertainties in the interconnection dynamics. A consensus-based estimator with timevarying weights is introduced, for improving fault detectability in the case of variables shared among more than one subsystem. Furthermore, time-varying threshold functions are designed to prevent false-positive alarms. Analytical fault detectability sufficient conditions are derived and extensive simulation results are presented to illustrate the effectiveness of the distributed fault detection technique
Tribological Studies on Scuffing Due to the Influence of Carbon Dioxide Used as a Refrigerant in Compressors
The refrigeration and air conditioning industry has expressed a great interest in the use of carbon dioxide
(CO2) as a refrigerant. CO2 is anticipated to replace HFC refrigerants, which are known to have a negative effect on
the environment. The reason behind the interest in CO2 is the fact that it is a natural refrigerant, thus
environmentally acceptable. Of course, such a replacement raises concerns regarding design criteria and
performance due to the different thermodynamic properties of CO2 and the very different range of pressures required
for the CO2 refrigeration cycle.
So far, work related to CO2 has been done from a thermodynamics point of view and researchers have
made significant progress developing automotive and portable air-conditioning systems that use the environmentally
friendly carbon dioxide as a refrigerant. The purpose of this work is to develop an understanding of how CO2 plays
a role from a tribology standpoint. More specifically, the goal of this work is to gain an understanding on how CO2
influences friction, lubrication, wear and scuffing of tribological pairs used in compressors.
Work in the area of tribology related to CO2 is very limited. Preliminary work by Cusano and coworkers
showed that consistent data for tests using CO2 could not be acquired nor could a satisfactory explanation be offered
for the inconsistency. Their results triggered the initiation of the work presented here. In this first attempt to
understand the tribological behavior of CO2 several problems were encountered. During this work we noted that its
behavior, unlike conventional refrigerants, could not always be predicted. We believe that this can be attributed to
the thermodynamic properties of CO2, which cannot be ignored when studying its tribological behavior.
Thermodynamic Properties such as miscibility are very important when tribological testing is performed. A limiting
factor with our tester was that it was not designed for CO2 testing, but for other conventional refrigerants and
therefore made previously developed testing protocols non-applicable with CO2. Through a different approach and
some modifications to our tester we were able to establish a protocol for testing under the presence of CO2. CO2
was then compared to R134a and the experimental results showed that it performs equally well.Air Conditioning and Refrigeration Project 13
High-frequency techniques for RCS prediction of plate geometries and a physical optics/equivalent currents model for the RCS of trihedral corner reflectors
Part 1 of this report continues the investigation, initiated in previous reports, of scattering from rectangular plates coated with lossy dielectrics. The hard polarization coefficients given in the last report are incorporated into a model, which includes second- and third-order diffractions, for the coated plate. Computed results from this model are examined and compared to measured data. A breakdown of the contribution of each of the higher-order terms to the total radar cross section (RCS) is given. The effectiveness of the uniform theory of diffraction (UTD) model in accounting for the coating effect is investigated by examining a Physical Optics (PO) model which incorporates the equivalent surface impedance approximation used in the UTD model. The PO, UTD, and experimental results are compared. Part 2 of this report presents a RCS model, based on PO and the Method of Equivalent Currents (MEC), for a trihedral corner reflector. PO is used to account for the reflected fields, while MEC is used for the diffracted fields. Single, double, and triple reflections and first-order diffractions are included in the model. A detailed derivation of the E(sub theta)-polarization, monostatic RCS is included. Computed results are compared with finite-difference time-domain (FDTD) results for validation. The PO/MEC model of this report compares very well with the FDTD model, and it is a much faster model in terms of computational speed
Distributed Adaptive Fault-Tolerant Control of Uncertain Multi-Agent Systems
This paper presents an adaptive fault-tolerant control (FTC) scheme for a
class of nonlinear uncertain multi-agent systems. A local FTC scheme is
designed for each agent using local measurements and suitable information
exchanged between neighboring agents. Each local FTC scheme consists of a fault
diagnosis module and a reconfigurable controller module comprised of a baseline
controller and two adaptive fault-tolerant controllers activated after fault
detection and after fault isolation, respectively. Under certain assumptions,
the closed-loop system's stability and leader-follower consensus properties are
rigorously established under different modes of the FTC system, including the
time-period before possible fault detection, between fault detection and
possible isolation, and after fault isolation
Synthesis of Realistic Simultaneous Positron Emission Tomography and Magnetic Resonance Imaging Data
The investigation of the performance of different positron emission tomography (PET) reconstruction and motion compensation methods requires accurate and realistic representation of the anatomy and motion trajectories as observed in real subjects during acquisitions. The generation of well-controlled clinical datasets is difficult due to the many different clinical protocols, scanner specifications, patient sizes, and physiological variations. Alternatively, computational phantoms can be used to generate large data sets for different disease states, providing a ground truth. Several studies use registration of dynamic images to derive voxel deformations to create moving computational phantoms. These phantoms together with simulation software generate raw data. This paper proposes a method for the synthesis of dynamic PET data using a fast analytic method. This is achieved by incorporating realistic models of respiratory motion into a numerical phantom to generate datasets with continuous and variable motion with magnetic resonance imaging (MRI)-derived motion modeling and high resolution MRI images. In this paper, data sets for two different clinical traces are presented, ¹⁸F-FDG and ⁶⁸Ga-PSMA. This approach incorporates realistic models of respiratory motion to generate temporally and spatially correlated MRI and PET data sets, as those expected to be obtained from simultaneous PET-MRI acquisitions
A Robust Nonlinear Observer-based Approach for Distributed Fault Detection of Input-Output Interconnected Systems
This paper develops a nonlinear observer-based approach for distributed fault detection of a class of interconnected
input–output nonlinear systems, which is robust to modeling uncertainty and measurement
noise. First, a nonlinear observer design is used to generate the residual signals required for fault detection.
Then, a distributed fault detection scheme and the corresponding adaptive thresholds are designed
based on the observer characteristics and, at the same time, filtering is used in order to attenuate the effect
of measurement noise, which facilitates less conservative thresholds and enhanced robustness. Finally, a
fault detectability condition characterizing quantitatively the class of detectable faults is derived
Austerity and the income distribution: The case of Cyprus
The economic crisis affecting Cyprus is likely to have considerable impact on the income distribution. Our analysis provides an early assessment of the short-run distributional effects of austerity measures. We distinguish between fiscal measures that affect wages, taxes and contribution rates and measures that directly affect the function of the welfare system. Using the tax-benefit EUROMOD model we attempt to quantify the distributional implications of both. The analysis focuses on the policy changes introduced over the period between 2011 and 2012, i.e. before the expected bailout deal between the government of Cyprus and the consortium of international lenders which is expected in spring 2013. Specifically, we simulate the ceteris paribus impact of the reforms on inequality and poverty as well as estimate how the burden of austerity has been shared across income groups
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