Crack initiation and propagation resistance of hsla steel welded joint constituents

The welded joint is heterogeneous in its microstructure, mechanical and geometrical properties, thus the stress field is affected by different factors as well as by residual stress. Therefore, special procedures are needed for experimentally determining the fracture toughness in plane strain, K-Ic, and the impact toughness, usually associated with difficulties in interpreting the measured values. Notched specimens are tested by instrumented Charpy in order to determine impact energy and crack initiation and propagation energies. The pre-cracked specimens are tested by standard, using three-point bending specimens, as geometrically closest to Charpy specimens. In both cases, the notch and crack are located in all various regions of the welded joint of the high-strength low alloyed steel NIONIKRAL-70. Analysis of the results includes speculations on the ratio of energies for crack initiation and propagation vs. fracture toughness

Crack initiation and propagation resistance of hsla steel welded joint constituents

The welded joint is heterogeneous in its microstructure, mechanical and geometrical properties, thus the stress field is affected by different factors as well as by residual stress. Therefore, special procedures are needed for experimentally determining the fracture toughness in plane strain, K-Ic, and the impact toughness, usually associated with difficulties in interpreting the measured values. Notched specimens are tested by instrumented Charpy in order to determine impact energy and crack initiation and propagation energies. The pre-cracked specimens are tested by standard, using three-point bending specimens, as geometrically closest to Charpy specimens. In both cases, the notch and crack are located in all various regions of the welded joint of the high-strength low alloyed steel NIONIKRAL-70. Analysis of the results includes speculations on the ratio of energies for crack initiation and propagation vs. fracture toughness

Topological phase transition in a RNA model in the de Gennes regime

We study a simplified model of the RNA molecule proposed by G. Vernizzi, H. Orland and A. Zee in the regime of strong concentration of positive ions in solution. The model considers a flexible chain of equal bases that can pairwise interact with any other one along the chain, while preserving the property of saturation of the interactions. In the regime considered, we observe the emergence of a critical temperature T_c separating two phases that can be characterized by the topology of the predominant configurations: in the large temperature regime, the dominant configurations of the molecule have very large genera (of the order of the size of the molecule), corresponding to a complex topology, whereas in the opposite regime of low temperatures, the dominant configurations are simple and have the topology of a sphere. We determine that this topological phase transition is of first order and provide an analytic expression for T_c. The regime studied for this model exhibits analogies with that for the dense polymer systems studied by de GennesComment: 15 pages, 4 figure

Comparative analyses of built environment exposures relevant to health of greenhouse gas emissions reduction strategies in Serbia

Paper presents comparative analysis of residential indoor air pollutant concentration change over future specified time horizon, implementing building physical and thermal retrofit measures, thus creating pollution mitigation scenarios for existing Belgrade and Nis housing stock followed by greenhouse gas emission reduction scenarios up to 2050. Regarding specified mitigation scenarios, the set of typical housing unit models has been generated which define existing housing stock of Belgrade and Nis. Extensive monitoring of physical and thermal parameters as well as detailed socio-technical survey of selected households was performed and used as an initial modeling input. Relationship between environment pollution and building performances was investigated, with respect to indoor-outdoor sources of pollution, thermal and physical properties of the stock samples and occupant's behavior. As a final output, indoor pollutant concentrations for each of the modelled cases was obtained and validated against the available data. This housing modelling framework has been created in order to develop an assessment of present and future exposure and health impact quantity regarding single/multiple scenario interventions introduced to the housing stock. This paper provides each strategy guidelines for taking measures towards achieving the healthier indoor environments

Observation of associated near-side and away-side long-range correlations in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT

Observation of Associated Near-Side and Away-Side Long-Range Correlations in sqrt[s_{NN}]=5.02 TeV Proton-Lead Collisions with the ATLAS Detector.

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in sqrt[s_{NN}]=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb^{-1} of data as a function of transverse momentum (p_{T}) and the transverse energy (ΣE_{T}^{Pb}) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) "near-side" (Δϕ∼0) correlation that grows rapidly with increasing ΣE_{T}^{Pb}. A long-range "away-side" (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣE_{T}^{Pb}, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣE_{T}^{Pb} dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣE_{T}^{Pb} ranges and particle p_{T}

Impact of plate types on refining and specific energy consumption

Fibre refining is one of the most important stages of mechanical and chemical fibre treatment with direct impact on the quality of the final product-paper. The raw material to be refined and the requirements regarding the final product quality determine the way and technology of refining (concentration, pH, pressure in the refiners, ratio of refining), arrangements of plates, rotor rotation number and micro frequency between the grooves and plates. In addition to these factors, influencing paper quality, the cost of fibre refining, i.e. specific energy consumption, is of equal importance. This research was developed in two directions: examination of the refining quality and specific energy consumption during refining. The plates made at the Faculty of Technology and Metallurgy in accordance with our own technology were cast in molds made of coated sand (sand coated with resin). These molds were zirconium coated before casting. Zirconium from the coat microalloys the molded material, thus essentially affecting the structure as well as hardness which, on the other band, influences the teeth sharpness after grinding. This affects the life of the refiner plates as well as the refining quality of pulp. The molds made of coated sand give refiner plates with smooth and flat surfaces, influencing the pulp flow and reducing the resistance of the pulp flow through the interteeth space of the refiner plates

Microstructural evolution and electric properties of mechanically activated BaTiO3 ceramics

Ceramic materials with a perovskite related structures such as non-doped and doped barium titanate ceramics are attracting much interest for their application as capacitor dielectrics, resistors, thermal sensors, etc. Since mechanical activation can be used in order to modify properties of these materials, in this study microstructure evolution and electric properties of mechanically activated BaTiO3 have been analyzed. The sintering process of high purity non-doped mechanically activated BaTiO3 was monitored using a sensitive dilatometer with a heating rate of 10 degrees C/min. Investigation of the microstructure evolution of mechanically activated BaTiO3 was performed using scanning electron microscope (SEM) and digital pattern recognition (DPR) methods. A dielectric study of the paraelectric-ferroelectric phase transition in the barium titanate ceramics was performed by recording the temperature dependence of dielectric permittivity

Correlation between densification rate and microstructure evolution of mechanically activated BaTiO3

Increasing demands on the quality of electronic ceramics requires a well-controlled correlation between particle morphology and processing conditions. Since mechanical activation is one of the methods for modification of physico-chemical properties of dispersed systems, in this study a correlation between the densification rate and microstructure evolution of mechanically activated BaTiO3 has been analyzed. The shrinkage behaviour of mechanically activated samples, sintered under non-isothermal conditions has been analyzed by a sensitive dilatometer. Densification rate as a function of relative density for different activation times has been calculated. Microstructure investigations of sintered samples were carried out, using a scanning electron microscope (SEM). The presented results enable establishing processing parameters that are indispensable for obtaining materials with advanced properties