1,720,991 research outputs found
A Thermodynamic Approach to the Definition of the HAT Cycle Plant Structure
No full textAn optimization procedure of the Humid Air Turbine (HAT) cycle plant structure is presented here aimed
at maximizing the total plant efficiency. The procedure is based on the design optimization of a ‘‘basic
configuration of the plant’’ including ‘‘basic components’’ (compressor, turbine, combustion chamber, regenerator
and saturator), always existing and connected in the same way in the plant structure, and the heat
exchanger section which is viewed as a ‘‘black-box’’ where the heat transfer between hot and cold thermal
flows occurs independently of the number and interconnections of the heat exchangers. The optimal
boundary conditions between basic components and black-boxare determined by means of a suboptimization
procedure performed in each step of the main optimization procedure using rules of Pinch Technology
and Second Law insights. Rules of pinch technology and second law insights are then used to
determine the heat exchanger networks (HENs) within the black-box that fulfill the optimum design conditions
at the black-boxbounda ries. Accordingly, ‘‘optimal’’ structures of the plant are determined by the
combination of basic components and ‘‘optimal’’ HENs. 2002 Elsevier Science Ltd. All rights reserved
Thermodynamic Optimization of the HAT Cycle Plant Structure. Part II: Structure of the Heat Exchanger Networks
No full textA method for the thermodynamic optimization of the humid air turbine cycle plant structure
is presented here. The method is based on the optimization of a ‘‘basic configuration
of the plant’’ including ‘‘basic components’’ (compressor, turbine, combustion chamber,
regenerator, and saturator), always present and connected in the same way in the plant
structure and a heat exchange section which is viewed as a ‘‘black-box’’ where the heat
transfer between hot and cold thermal flows occurs regardless of how many heat exchangers
there are and of how they are interconnected. The optimal boundary conditions
between the basic components and black-box are determined by calculating the conditions
of maximum heat transfer in the black-box independently of the structure of the heat
exchanger network. This is done by defining optimal composite curves in a Fortran
routine at each step in the main optimization procedure. Once the structure of the heat
exchanger networks that fulfill the optimal boundary conditions have been found, the
optimal structure of the whole plant is obtained (see Section 2). The method is useful in a
general sense as it can be applied to highly integrated energy systems in which it is
difficult to define the optimal structure of the heat exchanger network in advance.
@DOI: 10.1115/1.1338999
Implementing co-production in mental health organizations
Full text linkPurpose The purpose of this paper is to study four cases of the adoption of co-production and compare them according to the type of user involvement, contextual factors and the organizational structure. Design/methodology/approach In total, 30 interviews were conducted in four mental health organizations which are implementing co-production in the North of Italy. Interviews were conducted with clinicians, nurses, patients and family members. The data collected was triangulated with further sources and official documents of organizations. The results have been compared by means of a validated international framework (IAP2) regarding the contextual factors and the level of co-production adopted. Findings The adoption of co-production in the four cases differs by the activities implemented and how organizations involve informal actors. It seems to be influenced by the contextual factors specific to each organization: power, professionals' opinions and leadership. Organizations whose practitioners and leaders are willing to distribute their power and value informal actors' opinions seem to facilitate the systematic involvement of users. Overall, the results highlight the importance of considering contextual factors when evaluating and describing co-production activities. Originality/value This paper contributes to describing how mental health organizations are implementing co-production. It examines the influence of contextual factors on the type of co-production adopted
Secondary ion mass spectrometry and optical characterization of Ti : LiNbO3 optical waveguides
No full textSecondary ion mass spectrometry (SIMS) and m-lines spectroscopy have been applied to study Ti:LiNbO3 slab optical waveguides with high titanium surface concentration. By combining the two techniques, a saturation in the dependence of the refractive index change on the dopant concentration has been found. By the use of SIMS in image mode, the lateral diffusion of titanium in Ti:LiNbO3 channel waveguides has been observed and analyzed
Action Research as a Method to Find Solutions for the Burden of Caregiving at Hospital Discharge
Full text linkThe role played by family caregivers in delivering long-term care is crucial: they enhance the quality of care perceived by the patients and support the shift to out-of-hospital care. However, taking care of a relative entails a huge burden that usually begins with the patient’s hospital discharge and may mean that caregivers become patients in need of care as well. Owing to socio-demographic trends, informal caregiving is the most important source of care in community settings; hence targeting the caregivers’ burden properly is crucial. This study explores how action research (AR) can be used to develop new hospital practices to manage the burden borne by family caregivers when patients are discharged from hospital. The 7- month-long action research reported in this paper consisted of three stages (burden identification, burden sharing, and burden management) and it was conducted in a teaching hospital in Rome (Italy). Both quantitative (surveys) and qualitative (focus groups and simulation sessions) techniques were used to engage participants. The AR demonstrates that there is a feasible way in which hospital managers can address proactively the caregivers’ needs in the hospital discharge process, to the advantage of the patients and the entire communit
Correlation between optical and compositional properties of Ti : LiNbO3 channel optical waveguides
No full textOptical, compositional, and structural characterization of titanium-diffused LiNbO3 channel waveguides has been performed. The refractive index profiles have been reconstructed from near field measurements using a well-adapted mathematical approximation. Crystal lattice deformations have been measured by x-ray diffraction. Titanium concentration profiles measured by secondary ion mass spectrometry have been correlated to the refractive index profiles. The correlation between compositional, structural, and optical properties is discussed
Erbium incorporation in LiNbO3 crystals obtained by ion-exchange process
No full textErbium local doping of LiNbO3 single crystal by the ion-exchange has been performed. The role of the process parameters such as exchange time and temperature, crystal cut direction, composition and heating rate of the Er ions liquid source has been investigated by means of secondary ion mass spectrometry, X-ray diffraction and micro-lumi- nescence techniques. A theoretical model has been presented for describing the ion-exchange process and has been successfully applied to fit the experimental data. We have demonstrated that the method is suitable for Er-doping of LiNbO3 crystals, with the possibility of tailoring the optical performances of the material through the preparation parameters
Characterization of waveguides obtained by proton exchange on a LiNbO3 substrate
No full textWaveguides obtained by proton exchange in LiNbO3 were characterized by Secondary Ion Mass Spectrometry and m-lines technique. Additional micro-Raman investigations evidenced marked changes in the spectra of the waveguide with respect to the substrate. This suggests that micro-Raman spectroscopy may constitute a direct non-destructive method to determine the depth of the exchanged layer, with a limit which is set by the diffraction-limited spot size
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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