1,932 research outputs found
Land-use structure, urban growth, and periurban landscape: a multivariate classification of the European cities
Assessment of urbanization and suburbanization patterns and processes in the European Union is becoming increasingly urgent for the formulation of common territorial policies. We hypothesize that the intrinsic characteristics of landscape at the city scale reflect both the local socioeconomic context and the regional trends towards urbanization, possibly representing the contrasting attitude towards suburbanization found in European countries. Using comprehensive information provided by Urban Atlas maps, we propose an exploratory multivariate analysis of eighty-five variables describing land-use composition, landscape structure, and urban form in 283 cities with the aim being to classify the urbanization patterns observed in five European macroregions. Landscape metrics seem to be more powerful in discriminating cities among regions than indicators of land-use composition. The most relevant metrics discriminating among cities are (i) those describing fragmentation processes along the urban gradient and (ii) those evaluating form and patchiness of discontinuous settlements. Landscape and class average patch size and edge density correctly classified cities in more than 80% of cases. In particular, cities in Southern, Eastern, and Northern Europe were identified as three homogeneous groups as far as landscape structure is concerned, confirming the converging urbanization trends in the Mediterranean countries and the peculiar morphological characteristics of post-socialist urban areas
Passive house optimization for Southern Italy based on the “New Passivhaus Standard”
The IEE Passive-On project has drafted a proposal to adapt that Standard to the conditions that characterize Southern Europe, which is described in this paper together with its rationale. Compared with the original definition, one of the main changes is the introduction of explicit requirements on internal comfort during summer, in parallel to a limit to energy needs for cooling.
The dynamic simulations conducted to test the new definition of the Standard in the context of Southern Italy (e.g. Palermo) show that the requirements identified by the Passivhaus Standard can be met by simplifying the envelope technologies (e.g. relaxing air-tightness design value) used in the context of Central Europe and adopting passive cooling strategies appropriately adjusted. Some simplifications of the ventilation system can be compensated by an increased role of thermal insulation of the building envelope and some of the choices can make energy needs tend to zero. In accordance with EN15251, thermal comfort is characterized according to Fanger’s PMV in cases where mechanical cooling is still required for peak situations, and according to the adaptive model where no mechanical cooling is required
Combustion and performance characteristics of air-fuel mixtures ignited by means of photo-thermal ignition of Nano-Energetic Materials
Abstract This work presents an experimental investigation to determine the performance and characteristics of the combustion process triggered by a new ignition system based on photo-thermal effect, observed when nano-Energetic Materials are exposed to a flash light. The resulting combustion process has been compared with the one obtained using the spark-plug traditionally used in spark ignition engines. Results showed that the photo-thermal ignition determines higher combustion pressure gradient, peak pressure, total heat released, fuel combustion efficiency, and a shorter ignition delay and combustion duration compared with the spark ignition, for all the tested fuels and air-fuel ratios
Mixed Land Use as an Intrinsic Feature of Sprawl: A Short-Term Analysis of Settlement Growth and Population Distribution Using European Urban Atlas
This study investigates the land-use/population mix over time as the base to derive an indicator of urban sprawl. Land-use individual patches (provided by Urban Atlas, hereafter UA, with a detailed spatial geometry at 1:10,000 scale) were associated with the total (resident) population based on official statistics (census enumeration districts and other public data sources), providing a comprehensive mapping of the spatial distribution of population density by land-use class in a representative case study for the Mediterranean region (metropolitan Athens, Greece). Data analysis adopted a mix of statistical techniques, such as descriptive statistics, non-parametric curve interpolation (smoothing splines), and exploratory multivariate statistics, namely hierarchical clustering, non-metric multi-dimensional scaling and confirmative factor analysis. The results of this study indicate a non-linear gradient of density decline from downtown (dominated by compact settlements) to peripheral locations (dominated by natural land). Population density in agricultural land was locally high and increasing over time; this result suggests how mixed land use may be the base of intense sprawl in large metropolitan regions. The methodology implemented in this study can be generalized over the whole sample of European cities included in Urban Atlas, providing a semi-automatic assessment of exurban development and population re-distribution over larger metropolitan regions
Functional renormalization group at large N for random manifolds
We introduce a method, based on an exact calculation of the effective action
at large N, to bridge the gap between mean field theory and renormalization in
complex systems. We apply it to a d-dimensional manifold in a random potential
for large embedding space dimension N. This yields a functional renormalization
group equation valid for any d, which contains both the O(epsilon=4-d) results
of Balents-Fisher and some of the non-trivial results of the Mezard-Parisi
solution thus shedding light on both. Corrections are computed at order O(1/N).
Applications to the problems of KPZ, random field and mode coupling in glasses
are mentioned
Influence of the counter anion and steric hindrance of pyrazolyl and imidazolyl flexible ligands on the structure of zinc-based coordination polymers
Treatments of flexible 1,4-bis(3,5-dimethylpyrazolyl)butane (bbd), 1,4-bis(imidazolyl)butane (bib) and
1,4-bis(2-methylimidazolyl)butane (bmib) ligands with zinc salts at room temperature, resulted in the
formation of four novel metal\u2013organic coordination architectures: [ZnI2(l-bbd)]n (1), [Zn(NCS)2(l-bbd)]n
(2), {[Zn(l-bib)2](ClO4)2 (Et2O)0.5 (H2O)0.25}n (3) and {[Zn(l-bmib)2](ClO4)2 (H2O)4}n (4). X-ray crystallographic
analyses show different 1D and 3D polymeric structures for compounds 1\u20134 due to the variation
of the counter anions, solvent, steric hindrance and position of donating atoms in the structure of flexible
ligands. In 1 and 2, one-dimensional (1D) zig-zag polymeric chains are formed via metal centers and
l-bbd ligands. Complex 3 shows a 3-fold interpenetrated 3D architecture with 10^3-ths network topology.
In contrast to 3, in the structure of 4 neighboring Zn(II) ions are interconnected by a double-bridging
l-bmib ligands to form an infinite 1D polymeric double chain. The conformations of the flexible ligands
were analyzed in detail
Entangled Two-Dimensional Coordination Networks: A General Survey
Many of the reported species exhibit the intriguing feature of interpenetration or other types of entanglements. The properties of these materials are related not only to their molecular structures but also to the topology of the individual networks as well as to the way in which the individual nets are entangled. Different synthetic procedures have been developed to attain a certain control of entanglement in coordination networks, and recently some reviews have appeared that are focused on factors governing the entanglements, having in mind their potential applications. However, these analyses are mostly devoted to 3D networks thanks to the great wealth of data on interpenetration. Simplification of a network that contains 2-loops can lead to complete disappearance of the entanglement, and therefore such networks were picked out into a separate group
Adversarial Branch Architecture Search for Unsupervised Domain Adaptation
Unsupervised Domain Adaptation (UDA) is a key issue in visual recognition, as it allows to bridge different visual domains enabling robust performances in the real world. To date, all proposed approaches rely on human expertise to manually adapt a given UDA method (e.g. DANN) to a specific backbone architecture (e.g. ResNet). This dependency on handcrafted designs limits the applicability of a given approach in time, as old methods need to be constantly adapted to novel backbones.Existing Neural Architecture Search (NAS) approaches cannot be directly applied to mitigate this issue, as they rely on labels that are not available in the UDA setting. Furthermore, most NAS methods search for full architectures, which precludes the use of pre-trained models, essential in a vast range of UDA settings for reaching SOTA results.To the best of our knowledge, no prior work has addressed these aspects in the context of NAS for UDA. Here we tackle both aspects with an Adversarial Branch Architecture Search for UDA (ABAS): i. we address the lack of target labels by a novel data-driven ensemble approach for model selection; and ii. we search for an auxiliary adversarial branch, attached to a pre-trained backbone, which drives the domain alignment. We extensively validate ABAS to improve two modern UDA techniques, DANN and ALDA, on three standard visual recognition datasets (Office31, Office-Home and PACS). In all cases, ABAS robustly finds the adversarial branch architectures and parameters which yield best performances. https://github.com/lr94/abas
Three Cationic: Nonporous CuI-Coordination Polymers: Structural Investigation and Vapor Iodine Capture
Three cationic nonporous copper(I) coordination polymers containing bis-pyrazolyl flexible ligands have been prepared and characterized, namely, [Cu(\u3bc-bdb)1.5](PF6)n (1), [Cu(\u3bc-bpb)2](PF6)n (2), and [Cu(\u3bc-bpmb)2](PF6)n (3) (bdb = 1,4-bis(3,5-dimethylpyrazolyl) methyl)benzene; bpb = 1,4-bis(pyrazolyl)butane; bpmb = 1,4-bis(pyrazolyl)methyl)benzene). All compounds were characterized by infrared, powder X-ray diffraction, elemental and thermal analyses, and single-crystal X-ray diffraction. Compound 1, with methyl-substituted pyrazolyl ligand, forms a chain of alternating rings and ribbons in which the copper(I) centers are three coordinated in distorted trigonal planar geometry. In compounds 2 and 3 copper(I) atoms adopt distorted tetrahedral geometries giving two-dimensional sheet structures with 44-sql topology. Interestingly, iodine sorption experiments show that colorless crystals of 2 and 3 remain unchanged in the presence of iodine vapors, while the three-coordinated compound 1 immediately absorbs iodine and turns dark. Anion exchange behavior of compounds 1 and 2 was also investigated both in solution and in the solid state
Further insights into the beck hopelessness scale (BHS). Unidimensionality among psychiatric inpatients
Short versions of the Beck Hopelessness Scale have all been created according the Classical Test Theory, but the use and the application of this theory has been repeatedly criticized. In the current study, the Item Response Theory approach was employed to refine and shorten the BHS in order to build a reasonably coherent unidimensional scale whose items/symptoms can be treated as ordinal indicators of the theoretical concept of hopelessness, scaled along a single continuum. In a sample of 492 psychiatrically hospitalized, adult patients (51.2% females), predominantly with a diagnosis of Bipolar Disorder type II, the BHS was submitted to Mokken Scale Analysis. A final set of the nine best-fitting items satisfied the assumptions of local independency, monotonicity, and invariance of the item ordering. Using the ROC curve method, the IRT-based 9-item BHS showed good discriminant validity in categorizing psychiatric inpatients with high/medium suicidal risk and patients with and without suicide attempts. With high sensitivity (>.90), this newly developed scale could be used as a valid screening tool for suicidal risk assessment in psychiatric inpatients
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