Geometric Morphology of Granular Materials

We present a new method to transform the spectral pixel information of a micrograph into an affine geometric description, which allows us to analyze the morphology of granular materials. We use spectral and pulse-coupled neural network based segmentation techniques to generate blobs, and a newly developed algorithm to extract dilated contours. A constrained Delaunay tesselation of the contour points results in a triangular mesh. This mesh is the basic ingredient of the Chodal Axis Transform, which provides a morphological decomposition of shapes. Such decomposition allows for grain separation and the efficient computation of the statistical features of granular materials.Comment: 6 pages, 9 figures. For more information visit http://www.nis.lanl.gov/~bschlei/labvis/index.htm

Valence fuctuation and magnetic ordering in EuNi2(P1-xGex)2 single crystals

Unusual phases and phase transitions are seen at the magnetic-nonmagnetic boundary in Ce, Eu and Yb-based compounds. EuNi$_2$P$_{2}$ is a very unusual valence fluctuating Eu system, because at low temperatures the Eu valence stays close to 2.5 instead of approaching an integer value. Eu valence and thus the magnetic property in this system can be tuned by Ge substitution in P site as EuNi$_2$Ge$_{2}$ is known to exhibit antiferromagnetc (AFM) ordering of divalent Eu moments with $T_N$ = 30 K. We have grown EuNi$_2$(P$_{1-x}$Ge$_x$)$_2$ (0.0 $\leq$ $x$ $\leq$ 0.5) single crystals and studied their magnetic, thermodynamic and transport properties. Increasing Ge doping to $x >$ 0.4 results in a well-defined AFM ordered state with $T_N$ = 12 K for $x$ = 0.5. Moreover, the reduced value of magnetic entropy for $x$ = 0.5 at $T_N$ suggests the presence of valance fluctuation/ Kondo effect in this compound. Interestingly, the specific heat exhibits an enhanced Sommerfeld coefficient upon Ge doping. Subsequently, electronic structure calculations lead to a non-integral valence in EuNi$_2$P$_{2}$ but a stable divalent Eu state in EuNi$_2$Ge$_{2}$ which is in good agreement with experimental results.Comment: 7 pages, 8 figure

The crystal structure of benzyloxycarbonyl-(α-aminoisobutyryl)-L-alanyl methyl ester

Crystals of the title compound, C20,H29,N3,O6, are monoclinic, space group P2, with a = 8-839 (3), b = f10.818 (3), c = 11.414 (2) A, β = 95.69 (2)° Z = 2; final R = 0.053. The molecular conformation is defined by the following angles (φ, ψ): Aib-1 58- 1, 36.8; Aib-2 68.3, 18.6; Ala-3 (φ) -136.2°. The molecule adopts a type 111 β -turn conformation stabilized by an intramolecular hydrogen bond between the CO of the benzyloxycarbonyl group and the NH of the alanyl residue. The hydrogen-bond parameters are N···O 2-904 Å and ∠NH···O 156.9°

Thermal energy storage system using phase change materials: Constant heat source

The usage of phase change materials (PCM) to store the heat in the form of latent heat is increased, because large quantity of thermal energy is stored in smaller volumes. In the present experimental investigation paraffin and stearic acid are employed as PCMs in thermal energy storage (TES) system to store the heat as sensible and latent heat also. A constant heat source is used to supply heat transfer fluid (HTF) at constant temperature to the TES system. In the TES system PCMs are stored in the form of spherical capsules of 38 mm diameter made of high density poly ethylene (HDPE). The results of the investigation are related to the charging time and recovery of stored energy from the TES system

Ferromagnetic Ordering in CeIr2B2: Transport, magnetization, specific heat and NMR studies

We present a complete characterization of ferromagnetic system CeIr2B2 using powder x-ray diffraction XRD, magnetic susceptibility chi(T), isothermal magnetization M(H), specific heat C(T), electrical resistivity rho(T,H), and thermoelectric power S(T) measurements. Furthermore 11B NMR study was performed to probe the magnetism on a microscopic scale. The chi(T), C(T) and rho(T) data confirm bulk ferromagnetic ordering with Tc = 5.1 K. Ce ions in CeIr2B2 are in stable trivalent state. Our low-temperature C(T) data measured down to 0.4 K yield Sommerfeld coefficient gamma = 73(4) mJ/molK2 which is much smaller than the previously reported value of gamma = 180 mJ/molK2 deduced from the specific heat measurement down to 2.5 K. For LaIr2B2 gamma = 6(1) mJ/molK2 which implies the density of states at the Fermi level D(EF) = 2.54 states/(eV f.u.) for both spin directions. The renormalization factor for quasi-particle density of states and hence for quasi-particle mass due to 4f correlations in CeIr2B2 is 12. The Kondo temperature TK ~ 4 K is estimated from the jump in specific heat of CeIr2B2 at Tc. Both C(T) and rho(T) data exhibit gapped-magnon behavior in magnetically ordered state with an energy gap Eg ~ 3.5 K. The rho data as a function of magnetic field H indicate a large negative magnetoresistance (MR) which is highest for T = 5 K.While at 5 K the negative MR keeps on increasing up to 10 T, at 2 K an upturn is observed near H = 3.5 T. On the other hand, the thermoelectric power data have small absolute values (S ~ 7 {\mu}V/K) indicating a weak Kondo interaction. A shoulder in S(T) at about 30 K followed by a minimum at ~ 10 K is attributed to crystal electric field (CEF) effects and the onset of magnetic ordering. 11B NMR line broadening provides strong evidence of ferromagnetic correlations below 40 K.Comment: 10 pages, 11 figure

Network Management System for (FUTON-like) Radio-over- Fiber Infrastructure

EU-Project FUTON Radio-over-Fiber (RoF) infrastructure proposes high transmission rates at small antenna costs, implying competitive CAPEX for next generation networks. But to be cost-efficient, it needs to employ new network architectures and intelligent technology solutions for decreasing network operational costs. The RoF Network Manager manages the network equipment on the optical front haul between the Central Unit (CU) and all Remote Antenna Units (RAU)s connected by it, as well as the communication links, while enabling end-to-end service problem resolution and service quality management by the FUTON Middleware. Although a significant amount of prior research work can be found in the literature related to RoF, there is still significant lack of technologies concerning RoF networks management. RoF Manager and its sub-systems target to fill such gap, proposing a novel concept in the form of Channel Forwarding Table (CFT). RoF Manager follows an autonomous and generic network management framework, designed to be scalable in terms of adding new network elements (NEs). It targets multitechnology, multi-service and multi-vendor NEs in the network using Simple Network Management Protocol (SNMP). It can also provide alternative paths in case of failure. This work puts forward a new paradigm towards RoF management solution managing network performance, network faults, network security and configurations for convergent networks

Development of substitute high temperature creep resistant alloys

HIGH temperature creep resistant super strength alloys invariably contain considerable amounts of Ni,Co,W, etc. as alloying additions, in respect of which India lacks in raw material resources. Extensive work has been carried out on development of Cr-Mn-N type austenitic steels as substitute for 18 Cr 8 Ni austenitic stainless steel and their aging behaviour have been extensively studied at the National Metallurgical Laboratory in the last decade. The present work has been initiated to further study the high temperature creep behaviour of Cr-Mn-N type austenitic steels with a view to evolving suitable compositions and heat-treatment to obtain opti-mum high temperature creep strength and rupture ducti- lity in these alloys. In this group of steel Mn and N are used as the chief austenitic stabilizers besides C

Geomagnetic induction and conductive structures in north-west India

Magnetic disturbance events and quiet daily variation as recorded by the 1979 magnetometer array study in north-west India are analysed for evidence of electrical conductivity structures in the region. Contour maps of Fourier transform parameters are presented, and the disturbance event data are also reduced to sets of real and quadrature Parkinson arrows over a range of periods. A variety of conductive structures in the area are mapped, including some relatively shallow ones thought to be caused by sediments, as in the Ganga basin. More information is obtained on a major conductivity structure which strikes perpendicular to the Ganga basin into the foothills of the Himalayas; a second major conductivity structure is detected to lie to the west of the array area, and may be associated there with some aspect of the suture zone of India and Asia