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Offshore pipelines used for transportation of hydrocarbons in the oil industry are subjected to external pressure, internal pressure to ensure flow, temperature and axial compression which causes buckling. Finite element modeling was performed, and experiments were conducted on pipeline models made of stainless steel of grade SS304. Present research work focuses on the improvement in buckling strength of offshore pipelines stiffened with rectangular pin buckle arrestor along the length of a pipeline using finite element analysis and their experimental validation. The results of finite element analysis showed that an offshore pipeline model without buckle arrestors has a buckling load of 4.69 kN whereas offshore pipeline stiffened with buckle arrestors of length 1000 mm along the length of a pipeline resulted in maximum buckling load of 14.075 kN. Accordingly, pipeline models were fabricated for conducting experiments. Comparison of finite element analysis results and experimental outcomes showed that the efficiency of buckle arrestor increased significantly by incorporating buckle arrestor along the length of a pipeline.

Present research work focuses on improving buckling strength of offshore pipelines by strengthening them with inclined stiffeners and inclined stiffeners with connecting rods. Eigenvalue buckling analysis was carried out using Finite Element Methods to find the buckling strength of the considered pipeline models. Seamless stainless steel pipe models of SS304 grade were considered for finite element analysis. The pipeline models were provided with inclined stiffeners whose angle of inclination varies from 100° to 176°. Connecting rods of different lengths is used to improve capacity of inclined stiffeners. In this paper, the effect of inclined stiffener configurations in improving the strength of offshore pipelines against buckling is presented. The finite element analysis results show that a pipeline strengthened with inclined stiffeners and inclined stiffeners with connecting rod showed improved buckling load carrying capacity.

Offshore pipelines are subjected to various forces, depending on the subsea conditions such as temperature, axial forces, pressure (internal and external), bending, and earthquake forces. The response of offshore pipelines in with-standing these forces involves elastic response as well as inelastic response. Buckle arrestors are installed at regular intervals along the length of the pipeline to prevent buckling occurring due to a combination of forces. Present research work focuses on the improvement in buckling strength of offshore pipelines which are stiffened with 3 different types of buckle arrestors. Buckling experiments were conducted on pipeline models fabricated from seamless stainless steel pipes of grade SS304. The pipeline models stiffened with three different buckle arrestors configurations; longitudinal continuous stiffener, sinusoidal stiffener, and angular stiffener. The purpose of our research is to study the effectiveness of buckle arrestor configuration in improving resistance to buckling and to identify optimum buckle arrestor configurations and their applicability to offshore pipelines. The study was conducted by finite element simulation of buckle arrestors using ANSYS. The stainless steel pipe models of 1 m length, 16 mm outer diameter, 11.8 mm inner diameter, 2.1 mm thickness are considered for finite element analysis and for conducting experiments. The results obtained from finite element analysis and experiment results show that the efficiency of buckle arrestor found to be more in case of pipeline stiffened with longitudinal continuous buckle arrestors.

A commercial Al–Si–Mg composite was diluted to different SiC (mean size: 8 µm) contents, and was foamed using TiH2 by melt based technique at a fixed foaming temperature. Foams with high expansions were achieved and uniform cell morphology is obtained at and below 10 vol% SiC. Despite good expansions, certain amount of foam collapse occurs for 5 vol% SiC composite. This work brings out that presence of SiC alone can lead to good foaming but these foams are unstable prior to solidification. This instability can be correlated to in situ oxide content. Both compression and impact (perforation) tests show improved properties with the increase in foam density. Compressive strength is not influenced by SiC content, and energy absorption too seems to be insensitive to the rate of loading within six orders of magnitude.

PES bands due to ionization from n*, n and π orbitals of the NO group in some aliphatic nitroso compounds have been identified. In nitrosobenzene derivatives only the n*(NO) band can be assigned unequivocally. Substituent effects on the ionization energies in aliphatic and aromatic nitroso compounds have been correlated with substituent constants.

Metal nanoparticles of varying sizes can be prepared by physical as well as chemical methods. They exhibit many fascinating properties, the size-dependent metal to nonmetal transition being an important one. Metal nanoparticles capped by thiols can be organized into ordered one-, two- and three-dimensional structures and these structures have potential applications in nanodevices. In this context, organization of arrays of metal nanoparticles with a fixed number of atoms assumes significance.

Al–Si–Mg/SiCP foams were prepared by melt processing route with TiH2 as the blowing agent. The effects of foaming temperature (640 and 670 °C), SiCP size (12 and 21 μm), and volume % (5–20) on liquid foam expansion and subsequent collapse were studied. Irrespective of the particle size, significant collapse was observed in the liquid foam at 670 °C. At the lower foaming temperature of 640 °C, the liquid foam collapse was low to moderate, with finer and higher (15/20%) contents of SiCp resulting in low collapse and the best overall quality. Preferential segregation of particles to gas/metal interface, postulated by earlier investigators, was not observed in the present case. The presence of SiC within the cell walls induced brittleness, and created irrecoverable damage during the initial phase of compressive deformation. The compressive strength of the foams was lower than theoretical predictions. Minor defects such as porosity, present within the cell walls, might be responsible in lowering of the compressive strength.

Granular pile anchors are innovative and effective in resisting the uplift pressure exerted on the foundation by a swelling expansive soil. In a granular pile anchor, the foundation is anchored at the bottom of the granular pile to an anchor plate with the help of a mild steel rod. This renders the granular pile tension-resistant and enables it to offer resistance to the uplift force exerted on the foundation by the swelling soil. This resistance to uplift or pull-out load depends mainly upon the shear parameters of the pile-soil interface and the lateral swelling pressure of the soil, which confines the pile radially and prevents it from being uplifted. The resistance to uplift can be increased by placing a base geosynthetic above the anchor plate so that it forms an integral part of the granular pile anchor. The increase in resistance is due to the friction mobilized between the geosynthetic and the confining media when the uplift load acts on the pile and the geosynthetic moves along with the pile. Hence it depends on the friction between the geosynthetic and the confining media and the area and stiffness of the geosynthetic. This paper discusses the effects of these parameters on pull-out load, rate of heave, and relative ground movement near the pile surface.Key words: expansive soil, granular pile anchor, base geosynthetic, ground movement, rate of heave, pull-out load.

In YBa2Cu3–yGayO7–δ, Ga can be substituted at the Cu(1) site up to y= 0.1 without change in structure, but this is accompanied by a slight decrease in the hole concentration and Tc; the same is true when Y is partly substituted by Ca, as in Y1–xCaxBa2Cu3–yGayO7–δ(0.0 0.2. The y= 0.3 and 0.4 compositions show metal–semiconductor transitions at 60 and 120 K, respectively, while the y= 0.6 composition is a semiconductor. When Y is partly substituted by Ca as in Y1–xCaxBaSrCu3–yGayO7–δ, the material is superconducting even when y= 0.3. All these Ga-substituted cuprates are in the underdoped region and accordingly Tc increases with increase in hole concentration.

1,4-Diphenyl-5-amino-1,2,3-triazole and 4-phenyl-5-anilino-1,2,3-triazole reactant: 35.7 g. (0.3 mole) of phenyl azide product: Six grams (0.025 mole) of 1,4-diphenyl-5-amino-1,2,3-triazole product: 4-phenyl-5-anilino-1,2,3-triazole Keywords: annulation, heterocyclic-[5]; cyclization, miscellaneous; rearrangements; assay methods, for 1,4-diphenyl-5-amino-1,2,3-triazole; assay methods, for 4-phenyl-5-anilino-1,2,3-triazole; 1,2,3-triazoles, 1,4-disubstituted-5-amino-, titration of

Bulk silver and nickel are less reactive than small clusters of these elements, as reactivity studies with O2 as well as with H2S and CO prove. The dissociation of O2 on small Ag clusters is favored, and the proportion of O2 molecules cleaved does not depend upon temperature, as is the case for larger clusters and silver metal. The change in reactivity is greatest at the metal–insulator transition—a finding that has implications for heterogeneous catalysis.

Based on in situ X-ray diffraction and EXAFS studies, it is shown that NiTiO3 formed by the reaction of TiO2(anatase) with Ni2+ during the calcination of Ni/TiO2, gives rise to Ni metal and TiO2(rutile) on reduction, a process that may be responsible for the strong interaction between the metal and the oxide support.

We have examined the magnetotransport properties and the structure, by Rietveld refinement of powder X-ray data, of the phases RE1.2Sr1.8Mn2O7(RE = La, Pr, Nd). We find that on cooling, La2Sr1.8Mn2O7 undergoes a transition to a nearly perfect ferromagnet with 90% magnetization at 1.45 T, as reported by earlier workers, but the Pr and Nd phases show only a small magnetization that grows gradually as the temperature is decreased. There seems to be significant correlation between electrical transport and the Jahn-Teller elongation of the apical Mn–O bonds in these systems. The elongation of the apical Mn-O bonds forces the nine-coordinate rock-salt site to be occupied preferentially by the smaller rare-earth-metal cations. This preferential occupation is reliably obtained from the X-ray refinement. All three title phases show a magnetoresistance ratio of about 4 (corresponding to a magnetoresistance, [R(0)–R(H)]/R(0), of about 75%) at a field of 7 T and temperatures around 100 K.

Evidence is presented for the strong interaction of nitrogen and oxygen with buckminsterfullerene.

V2O5 supported on ZrO2is found to be an excellent sensor for n-propane–butane mixtures at 625 K; in-situ X-ray diffraction studies show that V2O5 is reduced to VO2 with a metastable monoclinic structure on contact with the hydrocarbons and is oxidised back to the parent oxide on exposure to air.

The 2p core-level binding energies of Cu and Ni clusters increase while the kinetic energies of the LMM Auger lines decrease with decreasing cluster size. The shifts in the core-level binding energy and the Auger kinetic energy relative to the bulk metal are largest in the case of clusters deposited on an insulating substrate such as Al2O3 and least on amorphous carbon; shifts on TiO2 are intermediate between those on Al2O3 and carbon. The increase in core-level binding energies with decreasing cluster size signifies a metal to non-metal transition. The occurrence of such a transition is borne out more vividly by BIS studies. Accordingly, BIS studies on Pd clusters deposited on amorphous carbon clearly show that electron states are progressively introduced near the Fermi level with increase in cluster size. The chemical reactivity of transition-metal clusters varies with the size. Thus, the relative proportion of the atomic oxygen species increases with decreasing size of Ag clusters.

Nitrogen is dissociatively adsorbed on an annealed Ni/TiO2 surface just as on a Ti–Ni alloy surface while it is molecularly adsorbed on a Ni/Al2O3 surface.

The suitability of Galerkin's method for the solution of the problem of the finite deflection analysis of clamped skew sandwich plates is studied. The five coupled nonlinear governing differential equations for sandwich plates are transformed into nonlinear algebraic equations by using Galerkin's method of error minimization. These equations are then solved using an iterative algorithm suggested by Brown. Comparisons of the results of the present analysis with available solutions show good agreement. Numerical results are presented for skew sandwich plates for a wide range of values of the core modulus for different skew angles and aspect ratios. Simplicity in formulation and computation is the advantage of the method as compared with other methods of nonlinear analysis. Computing time and memory requirements in a digital computer are relatively very small, which makes the method attractive.

The Saint Venant's principle is accepted to be valid in most of the problems in structural mechanics. However, there are exceptions to this principle. The limitations of Saint Venant's principle as applied to sandwich type structures have been indicated by earlier researchers. The authors have already reported results of detailed numerical experiments on long rectangular strips. The aim of the investigation reported herein is to study the propagation of stress disturbance in the case of a sandwich medium subjected to an axisymmetric system of self-equilibrating loads, using a theory of elasticity approach. An infinite three-layer sandwich plate, subjected to two equal and opposite central concentrated loads, is considered. Three face-to-core modulus ratios are considered and representative numerical results are presented. In all cases it is observed that significant stresses do exist in the core at relatively large distances from the load point, compared to the homogeneous type of construction. The stress becomes negligible only at a distance of about four times the thickness of the plate from the load point in the case of very soft cores, the distance being less for more rigid cores.

The molecular structure of vinylidene chloride has been studied by the visual method using non-sectored and sectored plates and by the sector-microphotometer method. The results of the different methods are compared and discussed. The structural parameters have been found to be: C-C=1.324±0.020 A, C-Cl=1.710±0.010 A and ∠CICCl=14.5±1°.

The basic concepts of tuned half-wave lines were covered by Hubert and Gent [1]. In this paper the problem of overvoltages during faults and the stability of the system incorporating such tuned lines are discussed. The type of tuning bank and the line arrangements that will be satisfactory from the point of view of stability are suggested. The behavior of a line tuned by distributed capacitor is analyzed, and its performance is compared with the other type of tuned line.

This paper presents a method of finding an optimal linear voltage regulator for a single machine infinite bus power system. The performance criterion chosen is of the form The assumptions of controllability and observability are verified for the power system model. A method is suggested for choosing the weighting matrices Q and R from considerations of the transient response of the overall system. A detailed example of an automatic voltage regulator connected to a 30 MW machine is given for reference purpose.

This paper provides additional theoretical information on half-wave-length power transmission. The analysis is rendered more general by consideration of a natural half-wave line instead of a short line tuned to half-wave. The effects of line loading and its power factor on the voltage and current profiles of the line and ganerator excitation have been included. Some of the operating problems such as charging of the line and synchronization of the half-wave system are also discussed. The inevitability of power-frequency overvoltages during faults is established. Stability studies have indicated that the use of switching stations is not beneficial. Typical swing curves are also presented.

Ti and V sesquioxides and TiO-VO solid solutions crystallography and defect chemistry over entire range of compositions

This paper presents a comparison of the various types of regulators namely the current-actuated, the voltage-actuated the load angle-actuated and the rotor angle-actuated regulators, for a single machine infinite bus system. The same study is extended to a two machine system. The stability limit is given as the angle at which the critical eigenvalue of the system matrix changes sign.

From a screening of a few Ustilaginales fungi for free lysine accumulation, Sphacelotheca sorghi ITCC No. 591 was found to accumulate 50 ll-gfml of free lysine in the culture medium. However, it was later seen that the free lysine content of the culture broths could not be increased much unless cell lysis took place. Experiments were also carried out to increase the free lysine content of the culture broths of U. maydis PRL No. 1092. It was found that U. maydis maintained on sterilised corn, yields up to 400 p.g of free-L-1ysinejml in its culture medium in five days.

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Micrococcus glutamicus ATCC 13032, a glutamic acid-excreting organism, was mutated by treating a 6–8 h old culture with 0.2m ethyl methanesulfonate (EMS) in a phosphate buffer of pH 7.6 for 150 min. The auxotrophs isolated showed varied patterns of extracellular amino acids, 38 isolates excreted lysine up to 1–2 mg/ml but most lost their excretion potency in subsequent fermentation trials although they remained auxotrophic. Most of the auxotrophs showed a requirement for amino acids.

Thin paper presents a study of a simple intermittent regulator on a single machine infinite bus system. The method of analysis usedis Z-transform analysis. The power system is analysed as a feedback sampled-data control system.

Octahedral (O), tetrahedral (T), and square pyramidal (SP) co-ordination polyhedra of the transition metal ions are shown to coexist in oxides of the type Ca2Fe2–xMnxO5; these oxides transform on heating to the brownmillerite structure with only O and T co-ordination polyhedra.