Flow accelerated corrosion: Experience from examination of components from nuclear power plants

Flow accelerated corrosion (FAC) has affected a large number of components made from carbon steel in the secondary as well as primary circuits of light water reactors worldwide. This is primarily a corrosion process enhanced by (electro) chemical dissolution and mass transfer, rather than a mechanical process. It has caused rupture of all sizes of pipelines as well as other components carrying either single phase water or two phase (wet steam) flow. It is reported to be the only mechanism that has significant potential for large leaks in the secondary circuit. This paper describes the observations from examination of a number of components that were affected by FAC in Pressurized Heavy Water Reactors in the past 5 years. Failure analysis done on the 10% feed water line, non-return valve (NRV) in the auxiliary feed water system and on the affected pipeline components from the secondary water system of various reactors has been described in this paper. The surface features observed (the signature pattern of FAC) on the inner surfaces of the pipelines affected by FAC in the primary and the secondary circuits of nuclear reactors have been described. Signature patterns of FAC, on components severely affected by single phase FAC (scallops) and on components affected by dual phase FAC (tiger striping) are recorded and reported. Components where FAC degradation had just initiated showed that the patterns were not well defined. The signature patterns became evident only after the degradation had occurred to a large extent. FAC like features were not seen in stainless steel components in the secondary side. Case studies showing that thinning of carbon steel components is not always attributable to FAC in the secondary circuit of the reactors are also described and reasons of these thinning illustrated to show the importance of establishing the cause of each thinning case. The paper also discusses if the size of the scallops is possible to be correlated to the FAC rate.     

Value and productivity in the Internet economy

Internet technologies and applications have grown more rapidly than anyone could have envisioned just five years ago, opening up new frontiers of interaction between consumers, businesses and trading partners. What started out as haphazard compilations of company brochureware or static personal Web pages with images that users merely shared with friends and family has quickly evolved into a myriad of highly sophisticated online applications and business processes. Forward-thinking companies are leveraging the Internet's massive public technology infrastructure to create new value for their stakeholders and to attain new heights in productivity. The paper discusses the structure of the Internet economy     

D.C. electrical properties of vacuum-deposited CdTe films

The current-voltage characteristics of vacuum-deposited CdTe films were studied as a function of film thickness (2500–13000 Å) at various temperatures (0–110°C). The d.c. conduction mechanism was explained using a modified Poole-Frenkel equation.     

Computational Insights into the Deleterious Impacts of Missense Variants on N-Acetyl-d-glucosamine Kinase Structure and Function

An enzyme of the mammalian amino-sugar metabolism pathway, N-acetylglucosamine kinase (NAGK), that synthesizes N-acetylglucosamine (GlcNAc)-6-phosphate, is reported to promote dynein functions during mitosis, axonal and dendritic growth, cell migration, and selective autophagy, which all are unrelated to its enzyme activity. As non-enzymatic structural functions can be altered by genetic variation, we made an effort in this study aimed at deciphering the pathological effect of nonsynonymous single-nucleotide polymorphisms (nsSNPs) in NAGK gene. An integrated computational approach, including molecular dynamics (MD) simulation and protein–protein docking simulation, was used to identify the damaging nsSNPs and their detailed structural and functional consequences. The analysis revealed the four most damaging variants (G11R, G32R, G120E, and A156D), which are highly conserved and functional, positioned in both small (G11R and G32R) and large (G120E and A156D) domains of NAGK. G11R is located in the ATP binding region, while variants present in the large domain (G120E and A156D) were found to induce substantial alterations in the structural organizations of both domains, including the ATP and substrate binding sites. Furthermore, all variants were found to reduce binding energy between NAGK and dynein subunit DYNLRB1, as revealed by protein–protein docking and MM-GBSA binding energy calculation supporting their deleteriousness on non-canonical function. We hope these findings will direct future studies to gain more insight into the role of these variants in the loss of NAGK function and their role in neurodevelopmental disorders.     

Supply chain cell activities for a consumer goods company

The supply chain cell is a new cross-functional area in many industries in India. It involves the integration of production planning, dispatch order generation and logistics planning, apart from general logistics, which primarily includes distribution. This paper deals with the study conducted for a fast moving consumer goods company having 14 production locations and 22 branches/clearing and forwarding agents. There were 36 packing lines, with each line packing different varieties of stock-keeping units. In this company, supply chain cell activities were concentrated on the middle of the classical supply chain. An attempt has been made to integrate production logic with the logistics by considering the total cost concept. The total cost concept also includes non-quantifiable parameters, which have been incorporated by the use of the analytical hierarchy process. An optimization technique has been proposed simultaneously to support the planning logic developed. The supply chain cell helps to optimize the total supply chain cost as well as enabling it to supplement other benefits such as an improvement in inventory turnover and a reduction in the inventory carrying cost.     

Electrical and structural characterization of PTCR pure BaTiO3 nanopowders synthesized by sol–gel emulsion technique

BaTiO₃ ceramics have been widely studied for its application as multilayer ceramic capacitors. However, they have been reported to deviate from their insulating to semiconducting behavior upon doping, and are used as positive temperature coefficient (PTC) thermistors and transducers. In this work, sol–gel emulsion technique was used for synthesis of BaTiO₃ powders of various shapes and sizes. The synthesized powders were calcined at two different temperatures i.e. 750°C, and 1000°C. XRD revealed the powders to be primarily cubic in structure. Presence of tetragonality was noted in the powders calcined at 1000°C. Crystallite size was calculated for the powders calcined at 750°C and 1000°C. Average particle size of the prepared powders varied from 42 to 94?nm. The shape and size of the particles were dependent on the type and concentration of the surfactant used. The synthesized material showed positive temperature coefficient of resistivity (PTCR) behavior. From the recorded resistivity values a maximum of 10¹⁰ Ωcm was achieved. The ferroelectric to paraelectric transition temperature, Curie point, (T_c) was found to be at 75°C from the impedance spectroscopy analysis for the prepared material.     

Study of the active layer in hydrogenated amorphous silicon solar cells using electrical and analytical techniques

An attempt was made to understand the distribution of defect states in the active layers of p-i-n hydrogenated amorphous silicon solar cells. Capacitance-Voltage (CV) measurements were used to study the defect distribution in the i-layer, both in the bulk as well as near the p-i interface for cells fabricated on different substrates. The effect of inserting a buffer layer between the p and i-layers were also investigated. A combination of secondary ion mass spectroscopy (SIMS), secondary neutral mass spectroscopy (SNMS) and electron spectroscopy for chemical analysis (ESCA) measurements were used to study the elemental distribution in the active layer, specially those of the elements for the neighbouring p and transparent conducting oxide (TCO) layers. The X-ray, electron and ion beam probes when combined with the electrical analysis not only help to determine the cell structure resulting in optimum i-layer performance (both near the p-i interface and the bulk) but also gave an indication of the desired growth conditions of the i-layer.     

Comments, on `A novel digital phase meter' by K.M. Ibrahim andM.A.H. Abdul-Karim

It is pointed out that a circuit given in Fig.4 of the above-titled paper (ibid., vol.36, no.3, p.711-16, 1987) will not operate if the output of the divide by 2 counter is connected to the AND gate as it is shown     

Baring it all to software: Raw machines

The most radical of the architectures that appear in this issue are Raw processors-highly parallel architectures with hundreds of very simple processors coupled to a small portion of the on-chip memory. Each processor, or tile, also contains a small bank of configurable logic, allowing synthesis of complex operations directly in configurable hardware. Unlike the others, this architecture does not use a traditional instruction set architecture. Instead, programs are compiled directly onto the Raw hardware, with all units told explicitly what to do by the compiler. The compiler even schedules most of the intertile communication. The real limitation to this architecture is the efficacy of the compiler. The authors demonstrate impressive speedups for simple algorithms that lend themselves well to this architectural model, but whether this architecture will be effective for future workloads is an open question