A Wedge-DCB Test Methodology to Characterise High Rate Mode-I Interlaminar Fracture Properties of Fibre Composites

A combined numerical-experimental methodology is presented to measure dynamic Mode-I fracture properties of fiber reinforced composites. A modified wedge-DCB test using a Split-Hopkinson Bar technique along with cohesive zone modelling is utilised for this purpose. Three different comparison metrics, namely, strain-displacement response, crack propagation history and crack opening history are employed in order to extract unique values for the cohesive fracture properties of the delaminating interface. More importantly, the complexity of dealing with the frictional effects between the wedge and the DCB specimen is effectively circumvented by utilising right acquisition techniques combined with an inverse numerical modelling procedure. The proposed methodology is applied to extract the high rate interlaminar fracture properties of carbon fiber reinforced epoxy composites and it is further shown that a high level of confidence in the calibrated data can be established by adopting the proposed methodology

Identification of major factors influencing ELISpot-based monitoring of cellular responses to antigens from mycobacterium tuberculosis

A number of different interferon-c ELISpot protocols are in use in laboratories studying antigen-specific immune responses. It is therefore unclear how results from different assays compare, and what factors most significantly influence assay outcome. One such difference is that some laboratories use a short in vitro stimulation period of cells before they are transferred to the ELISpot plate; this is commonly done in the case of frozen cells, in order to enhance assay sensitivity. Other differences that may be significant include antibody coating of plates, the use of media with or without serum, the serum source and the number of cells added to the wells. The aim of this paper was to identify which components of the different ELISpot protocols influenced assay sensitivity and inter-laboratory variation. Four laboratories provided protocols for quantifying numbers of interferon-c spot forming cells in human peripheral blood mononuclear cells stimulated with Mycobacterium tuberculosis derived antigens. The differences in the protocols were compared directly. We found that several sources of variation in assay protocols can be eliminated, for example by avoiding serum supplementation and using AIM-V serum free medium. In addition, the number of cells added to ELISpot wells should also be standardised. Importantly, delays in peripheral blood mononuclear cell processing before stimulation had a marked effect on the number of detectable spot forming cells; processing delay thus should be minimised as well as standardised. Finally, a pre-stimulation culture period improved the sensitivity of the assay, however this effect may be both antigen and donor dependent. In conclusion, small differences in ELISpot protocols in routine use can affect the results obtained and care should be given to conditions selected for use in a given study. A pre-stimulation step may improve the sensitivity of the assay, particularly when cells have been previously frozen

Učinci konjske rotkvice (Moringa oleifera) kao dodatka prehrani na antioksidacijski status junica križanki različitih pasmina

The experiment was conducted to evaluate the anti-oxidant effect of Moringa oleifera meal-supplementation in the total mixed ration, replacing the compounded concentrate mixture for crossbred heifer calves. A total of twenty-one crossbred heifer calves were selected and grouped into three treatments based on body weight and age. The leaves (84%) and soft twigs (16%) of Moringa oleifera were mixed to prepare the Moringa oleifera meal. Compounded concentrate mixture, ground nut straw, hybrid napier grass, mineral mixture and common salt were used at 50, 23, 25, 1 and 1%, respectively to formulate the control total mixed ration (T1). The compounded concentrate mixture was replaced with the Moringa oleifera meal at 5.0 and 7.5 % to formulate total mixed rations T2 and T3. The whole blood was collected from each calves in the morning before feeding and watering at the beginning (0 day), middle (at 60 day) and end (at 126 day) of the experiment. The total leukocyte counts, total erythrocyte counts, haematocrit and platelet count of crossbred heifer calves differed non-significantly (P>0.05) between the treatment groups, and were within normal physiological range. The serum albumin, glucose, creatinine, urea, alkaline phosphatase, alanine amino transaminase, calcium and phosphorus differed non-significantly between the treatment groups. However, feeding with Moringa oleifera resulted in higher (P0.05) higher after feeding with the 5.0 and 7.5% Moringa oleifera meals. Feeding with 5.0 and 7.5% Moringa oleifera meal in the total mixed ration, replacing the high protein compounded concentrate mixture, to growing crossbred heifer calves had no adverse effect on haematological and biochemical constituents, and resulted in a non-significant (P>0.05) higher antioxidant capacity in the crossbred heifer calves.Ovo je istraživanje provedeno kako bi se procijenio antioksidacijski učinak konjske rotkvice (Moringa oleifera) kao zamjene za mješavinu koncentrata u hranidbi junica križanki različitih pasmina. Na temelju tjelesne mase i dobi, junice (n=21) su razvrstane u tri pokusne skupine. Lišće (84%) i mekše grančice (16%) konjske rotkvice izmiješane su kako bi se pripremio obrok za istraživane životinje. U formulaciji mješavine (T1) upotrijebljena je mješavina koncentrata u količini od 50%, mljeveni orašasti plodovi 23%, Hybrid Napier 25%, mineralna mješavina 1 % i obična sol 1 %. Pripreljena smjesa koncentrata zamijenjena je obrokom s konjskom rotkvicom u omjeru 5,0% i 7,5% za skupine T2 i T3. Od svake je junice uzet uzorak pune krvi ujutro prije hranjenja i pojenja na početku (0. dan), sredinom (60. dan) i na kraju pokusa (126. dan). Nije bilo statistički znakovite razlike (P>0,05) u ukupnom broju leukocita i eritrocita, hematokritu te broju trombocita među pokusnim skupinama i vrijednosti su bile unutar fiziološkog raspona. Ni u vrijednostima serumskog albumina, glukoze, kreatinina, ureje, alkalne fosfataze, alanin-aminotransaminaze, kalcija i fosfora nije bilo statistički znakovite razlike među pokusnim skupinama. Dodatak prehrani konjske rotkvice međutim rezultirao je porastom proteina u serumu (P0,05) pri hranjenju obrocima s dodatkom konjske rotkvice. Prehrana s 5,0 i 7,5% dodatka konjske rotkvice koja je zamijenila visokoproteinsku koncntriranu mješavinu u obrocima junica nije utjecala na njihove hematološke i biokemnijske pokazatelja kao ni na njihov antioksidacijski kapacitet čije neznatno povećanje nije bilo statistički znakovito (P>0,05)

Maximum Power Tracking System Based on Power Electronic Topology for Wind Energy Conversion System Applications

Wind energy has emerged as a dominant alternative power generation source. Conventional energy resources are depleting and their increasing cost cannot be ignored. Wind energy has taken an important role in replacing fossil fuels and nuclear energy. However, optimal exploitation of wind energy systems has remained a thought-provoking problem due to the nonlinear behavior of the wind speed. Distribution generation system and isolated micro-grid (MG) are mainly used in a wind energy system in order to utilize maximum potential of wind through the maximum power tracking algorithm based on DC-DC boost power electronic converter. In this paper, authors propose a technique which is effectively workable, highly reliable, of low cost and induces less mechanical stress on the wind generator system (WGS). Experimental results of the proposed system verify that the effectiveness near optimal WGS output power increased approximately up to 50%. Thus, better exploitation of the available wind power is obtained under low wind speeds

Characterizations of the diurnal shapes of OI 630.0 nm dayglow intensity variations: inferences

International audienceMeasurements of OI 630.0 nm thermospheric dayglow emission by means of the Dayglow Photometer (DGP) at Mt. Abu (24.6° N, 73.7° E, dip lat 19.09° N), a station under the crest of Equatorial Ionization Anomaly (EIA), reveal day-to-day changes in the shapes of the diurnal profiles of dayglow intensity variations. These shapes have been characterized using the magnetometer data from equatorial and low-latitude stations. Substantial changes have been noticed in the shapes of the dayglow intensity variations between 10:00?15:00 IST (Indian Standard Time) during the days when normal and counter electrojet events are present over the equator. It is found that the width (the time span corresponding to 0.8 times the maximum dayglow intensity) of the diurnal profile has a linear relationship with the integrated electrojet strength. Occasional deviation from this linear relationship is attributed to the presence of substantial mean meridional wind

Caju: a content distribution system for edge networks

More and more, users store their data in the cloud. While the content is then retrieved, the retrieval has to respect quality of service (QoS) constraints. In order to reduce transfer latency, data is replicated. The idea is make data close to users and to take advantage of providers home storage. However to minimize the cost of their platform, cloud providers need to limit the amount of storage usage. This is still more crucial for big contents. This problem is hard, the distribution of the popularity among the stored pieces of data is highly non-uniform: several pieces of data will never be accessed while others may be retrieved thousands of times. Thus, the trade-off between storage usage and QoS of data retrieval has to take into account the data popularity. This report presents our architecture gathering several storage domains composed of small-sized datacenters and edge devices; and it shows the importance of adapting the replication degree to data popularity. Our simulations, using realistic workloads, show that a simple cache mechanism provides a eight-fold ecrease in the number of SLA violations, requires up to 10 times less of storage capacity for replicas, and reduces aggregate bandwidth and number of flows by half.Les données des utilisateurs sont de plus en plus externalisées, stockées dans des clouds. Lors de la récupération des données, une certaine qualité de service doit être respectée. Afin de réduire la latence d'accès, les données sont répliquées. L'idée est de rapprocher les données des utilisateurs, mais également, de tirer avantage des systèmes de stockage du fournisseur chez l'utilisateur (les ''boxes''). Cependant, afin de minimiser le coût de leur plate-forme les opérateurs de cloud doivent limiter la quantité de stockage utilisée. Ceci est d'autant plus important que les données sont volumineuses. Ce problème est dur, les données ne sont pas toutes également populaires, la popularité est distribuée de manière très hétérogène: certaines données ne seront jamais accédées alors que d'autres seront demandées des milliers de fois. Le bon compromis entre l'utilisation de l'espace de stockage et la qualité de service doit donc prendre en compte la popularité des données. Ce rapport présente notre architecture qui rassemble plusieurs domaines de stockage composés de data-center de petite taille et de périphériques de bordure; il montre l'importance d'adapter le degré de réplication à la popularité des données. Nos simulations, montrent qu'un simple mécanisme de cache arrive a diviser par 8 le nombre de violations de SLA (Service Level Agreement) tout en nécessitant 10 fois moins de capacité de stockage

An integrated inverse numerical–experimental approach to determine the dynamic Mode-I interlaminar fracture toughness of fibre composites

A combined numerical–experimental methodology is presented to determine the dynamic Mode-I fracture properties of Fibre-Reinforced Polymer (FRP) composites. The experimental aspect consists of a modified Wedge-Double cantilever Beam (WDCB) test using a Split Hopkinson Pressure Bar (SHPB) set-up followed by a numerical inverse modelling strategy using cohesive-zone approach. The proposed method is inherently robust due to the use of three independent comparison metrics namely, the strain–displacement response, the crack length history and the crack opening history to uniquely determine the delamination properties. More importantly, the complexity of dealing with the frictional effects between the wedge and the DCB specimen is effectively circumvented by utilising appropriate acquisition techniques. The proposed methodology is applied to extract the high-rate interlaminar fracture properties of a carbon fibre reinforced composite, IM7/8552 and it is further shown that a high level of confidence in the calibrated data can be established by adopting the proposed methodology