Search results for " static"
showing 10 items of 62 documents
Seismic Behavior of Lisbon Mixed Masonry-RC Buildings With Historical Value: A Contribution for the Practical Assessment
2018
The fact that linear analysis is still the most used procedure in the design engineering offices, studies which addresses issues associated to the estimation of the structural behavior factor values are relevant. In this study, the behavior factor of a particular type of mixed masonry-reinforced concrete buildings in Lisbon is estimated. The typology chosen in this study represents 30% of building stock in Lisbon; these buildings were built between 1930 and 1960 and thus were designed without considering the seismic-design requirements proposed in current codes. The evaluation of the behavior factors was based on the use of nonlinear static analyses, performed in the form of the sensitivity…
Seasonal evolution of boundary layer heat content in the West African monsoon from the NCEP/NCAR reanalysis (1968-1998)
2000
Using the National Center for Environmental Prediction (NCEP)/National Centre for Atmospheric Research (NCAR) dataset over the period 1968–1998, the basic relationships between July and September monsoon circulation variations over West Africa and monthly meridional distribution of moist static energy (MSE) content in the boundary layer are portrayed. Wet minus dry stratified analyses relative to Sudan–Sahel rainfall show that particular April–June meridional patterns of near-surface MSE contents, south of 10°N, could control the amplitude and timing of the monsoon rainy season. Relative to the driest July–September situations, the wettest ones have been, on average, preceded by delayed but…
Spring to summer changes in the West African monsoon through NCEP/NCAR reanalyses (1968–1998)
2002
[1] This article focuses on the spring to summer evolutions of the West African monsoon from an energetic point of view; it uses NCEP/NCAR reanalyses along with observed and simulated rainfall data over the period 1968–1998. The results show that the West African monsoon can be viewed as a coupled ocean-atmosphere-land system phased with the zenithal evolution of solar radiation which maintains its thermally direct circulation by pumping, from the surface, enthalpy mainly in spring and latent energy in summer. In this context the horizontal energy gradients in the boundary layer play a key role during the spring to summer transition. At the beginning of spring, the moist static energy (MSE)…
Comportamento di una passerella pedonale strallata nei confronti delle azioni del vento
2007
The wind behaviour of a stayed footbridge has been analyzed. In order to avoid aeroelastic phenomena, an experimental campaign on a 1:15 scale model has been realized at the boundary-layer wind-tunnel of the Milan Polytechnic. The aerodynamic characterization of the structure has allowed to direct the project towards the choice of non-solid barriers, but with a medium porosity, by avoiding possible problems that can lead to ultimate limit state condi-tions of the structure (e.g., flutter or vortex shedding). In this way the quantitative effect of barriers has been estimated deducing reliable values not only for the alongwind forces, but also for the crosswind and torsional actions.
The relationship between the Sahelian and previous 2nd Guinean rainy seasons: a monsoon regulation by soil wetness?
2002
The correlation of 0.61 found between observed July–September Sahelian rainfall in year 0 and September–November Guinean rainfall in year - 1, led us to explore the statistical relationships between precipitation, soil moisture and near surface Moist Static Energy (MSE) gradients in West Africa. These analyses were performed over successive 30-year periods and specifically, the most recent period between 1968–1998. It is shown from observations, National Centers for Environmental Predictions and National Center for Atmospheric Research (NCEP/NCAR) reanalyses and from the Global Soil Wetness Project (GSWP) database, that wet Sahelian rainy seasons are preceded by abnormally wet soils over th…
Riferibilità dei contatori statici di energia reattiva in presenza di armoniche. Evoluzione normativa e prove sperimentali
2013
Traceability of static reactive energy meters in the presence of harmonics: theoretical considerations and a DAQ-based reference meter
2013
This paper deals with some problems related to the measurements traceability with static meters for reactive energy. These problems arise when the meters operate in the presence of harmonics, which can negatively affect their performances, depending on implemented metric. The paper analyzes the problem in the light of both in-force and draft standards, from the viewpoint of the performances of both commercial meters and reference standard instruments. The analysis is supported by some experimental tests, which are carried out by means of a reference meter, based on data acquisition boards, which can be used in both sinusoidal and distorted conditions.
Comorbid Fluency Difficulties in Reading and Math: Longitudinal Stability Across Early Grades
2018
We examined the prevalence of comorbidity of dysfluent reading and math skills longitudinally in a representative sample ( N = 1,928) and the stability of comorbid and single difficulties from first to fourth grades. The findings indicated that half the children who showed very low performance in one skill also evidenced low or very low performance in the other. Comorbid difficulties had somewhat higher prevalence in third and fourth graders than in first and second graders. The stability of comorbid difficulties was found to be established from Grade 2 onward, but the stability of single difficulties increased steadily across grades. Overall, the findings emphasize the relatively strong s…
Evaluation of Podalic Support and Monitoring of Balance Control in Children with and without Dyslexia: A Pilot Study
2020
Background: The American Psychiatric Association has identified dyslexia as a neurobiological disorder. The aim of the study was to evaluate podalic support, balance control, and dyslexia’s effects on interpersonal relationships. Methods: Fifty-seven subjects were enrolled for this study. The subjects were divided into two groups. The experimental group was composed of children with diagnosis of dyslexia. The control group was composed of healthy subjects. Each subject underwent baropodometry and posturographic analysis. In addition, the Multidimensional Self-esteem Assessment test by Bracken was used for a precise measurement of self-esteem in both groups (TMA). Results: The static b…