72 research outputs found
Local Reinforcemente Effect of Embedded Strain Gauges
No full textThe reinforcement effect of strain gauges installed on low Young's modulus materials has received
attention by many researchers with respect to both strain gauges installed on the surface [1,2] and
embedded inside the material [3,4].
In the case of strain gauges installed on the surface, the evaluation of the local reinforcement
effect gives [5] the following correction coefficient C, i.e. the ratio between the actual strain
(without the strain gauge) and the strain ' measured by the strain gauge:
*
' 1 sg
s
E
C
E
(1)
being
* sg g , sg
sg sg
sg sg sg
t L L
E E
L t t
(2)
where Esg is the Young’s modulus of the strain gauge, *
Esg is a characteristic of the strain gauge
which gives the strain gauge sensitivity to the reinforcement effect (reduced Young’s modulus of the
strain gauge), Es is the Young’s modulus of the specimen, tsg , Lg , Lsg are respectively thickness, total
gauge length and grid length of the strain gauge, and is the mean value of a function
determined by a theoretical analysis [5]. This paper concerns the local reinforcement effect of
embedded strain gauges that are frequently used especially inside plastic and composite materials
Stiffness and Reinforcement Effect of electrical Resistance Strain Gauges
No full textThe increasing use of low-modulus materials, on which the reinforcement effect of the electrical resistance strain gauge is not negligible, has re-opened the research interest into this issue. This study deals with the evaluation of stiffness, and of the strain gauge Young's modulus involved in the estimation of both the global and the local reinforcement effect; the relationship between the strain gauge stiffness and the local reinforcement effect is also analysed. In particular, the experimental technique used to determine the stiffness of some commercial strain gauges is described. The results show that the strain gauge stiffness alone does not permit an accurate evaluation of the local reinforcement effect
Are food intolerances and allergies increasing in immigrant children coming from developing countries ?
No full textThere are not available data concerning the occurrence, the clinical
features and the environmental risk factors for food intolerances and
allergies in immigrant children. The aim of the study was to evaluate
rates, distribution, clinical features and environmental risk factors for
food intolerances and allergies in immigrant children. Hospital records
of 4130 patients with celiac disease (CD), cow milk protein intolerance
(CMPI) and food allergies (FA) diagnosed in 24 Italian Centres from
1999 to 2001 were retrospectively reviewed, comparing immigrant patients
with Italian ones. 78/4130 (1.9%) patients were immigrant: 36/
1917 (1.9%) had CD, 24/1370 (1.75%) CMPI and 18/843 (2.1%) FA.
They were evenly distributed across Italy and their native areas were:
East Europe (23/78), Northern Africa (23/78), Southern Asia (14/78),
Saharan and Sub-Saharan Africa (9/78), Southern America (4/78), Far
East (3/7), Middle East (2/78). Despite differences in their origin, the
clinical features of immigrant children were similar to the ones of Italian
patients and among each ethnic group. The majority of them were born
in Italy (57/78) or have been residing in Italy since several years (19/78).
All of them had lost dietary habits of the native countries and had
acquired those of the Italian childhood population. Food intolerances
and allergies are present also in children coming from developing
countries, and paediatricians will need to have a full awareness of them
because the number of immigrant children in Italy is quickly increasing.
The clinical features of food intolerances and allergies appear the same
in each ethnic group, despite differences in races. Sharing of dietary
habits with the Italian childhood population seems to be an important
environmental risk factor
Experimental and numerical analysis of aluminum-aluminum bolted joints subject to an indentation process
No full textThe increasing interest of the industry (especially automotive, aviation and marine) in the fastener joints (riveted, bolted, etc.) between metallic materials, has re-opened the study on the possibility to improve the performance of the drilled structure using plastic deformation processes. Indentation process, performed before the drilling operation, creates circumferential compression stresses around the hole which increase significantly the mechanical performance of the drilled structures.
In this paper, static and the fatigue performances of aluminum–aluminum (AW 6082-T6) single-lap bolted joints are studied. In particular, the study compares the mechanical strength of only drilled single-lap bolted joints (OD specimens) and single-lap bolted joints subject to an indentation process (IP specimens). In order to determine the cycles to failure and the corresponding Wöhler diagram, several fatigue tests are performed. The analyses allow to determine the mechanical performance and the failure mode of the analyzed joints.
Several numerical analysis, conducted in ANSYS environment on three-dimensional models of the single-lap joint, are focused on the evaluation of the residual stress on the indented plate and, in particular, to compare the stress distribution on both type of analyzed joints
Phosphorylation of the AMPA receptor GluA1 subunit regulates memory load capacity
No full textMemory capacity (MC) refers to the number of elements one can maintain for a short retention interval. The molecular mechanisms underlying MC are unexplored. We have recently reported that mice as well as humans have a limited MC, which is reduced by hippocampal
lesions. Here, we addressed the molecular mechanisms supporting MC. GluA1 AMPA-receptors (AMPA-R) mediate the majority of fast excitatory synaptic transmission in the brain and are critically involved in memory. Phosphorylation of GluA1 at serine residues S831 and S845 is promoted by CaMKII and PKA, respectively, and regulates AMPA-R function in memory duration. We hypothesized that AMPA-R phosphorylation may also be a key plastic process for supporting MC because it occurs in a few minutes, and potentiates AMPA-R ion channel function. Here, we show that knock-in mutant mice that specifically lack both of S845 and S831 phosphorylation sites on the GluA1 subunit had reduced MC in two different behavioral tasks specifically designed to assess MC in mice. This demonstrated a causal link between AMPAR phosphorylation and MC. We then showed that information load regulates AMPA-R phosphorylation within the hippocampus, and that an overload condition associated with impaired memory is paralleled by a lack of AMPA-R phosphorylation. Accordingly, we showed that in conditions of high load, but not of low load, the pharmacological inhibition of the NMDA–CaMKII–PKA pathways within the hippocampus prevents memory as well as associated AMPA-R phosphorylation. These data provide the first
identified molecular mechanism that regulates MC
He voids lifetime control compared with buffer-layer engineering for a 600V punch-through IGBT
No full textDesign of IGBT with Integral Freewheeling Diode
No full textA new power structure integrating a freewheeling diode in the termination region of a punch-through (PT) insulated gate bipolar transistor (IGBT) is presented. The proposed solution requires virtually no silicon area penalty with respect to a standard IGBT. Static and dynamic experimental results show the correct behavior of both IGBT and freewheeling diode. Further, it is shown that the lateral diode surrounding the multicellular IGBT can support IGBT direct current with low on-state voltage drop. The operation mechanisms of the composite structure and design techniques to improve structure dynamic behavior are investigated through two-dimensional numerical device simulation
- …
