Technical note: Techniques to obtain improved predictions of global radiation from sunshine duration

Data for 42 stations in different parts of the world in the northern hemisphere have been employed to partition monthly averaged daily global radiation and sunshine duration in a bid to obtain improved fits to Angstroms correlation. It has been found that regression fits to the correlation using data for biannual groups of months from March–August (months 3–8) and September–February (months 9–2), or March–September (months 3–9) and October–February (months 10–2), give an improvement in the rms error over the year, which is 25% or higher than the errors for annual fits for half of the cases. In no case is there an increase in rms error from the partitioning.It is found that biannual regression parameters for a pyranometer station may be used to predict with good accuracy global radiation for locations hundreds of kilometers away from the station if the climate, altitude and latitude are similar.A use of the seasonal partitioning of data leads to the following relations with station independent coefficients for     

Standardization for advanced materials: experience and strategies for the future

Materials technology has been identified by most industrialized nations as a key enabling technology which will provide major economic and competitive advantages to industry. Numerous market forecasts show a strong growth potential in advanced materials applications in diverse industrial sectors. This paper discusses the need for standards and standardized methods for material specification and how this can stimulate the market by providing increased confidence in the design and performance of products. Only a limited number of standards exist for advanced materials, but recently there has been an upsurge of interest worldwide and some countries are very active in developing standards. This is illustrated for some key materials sectors such as advanced ceramics and polymer-matrix composites. Standardization of test and evaluation methods for advanced materials is seen by many countries as a priority area. Methods used for conventional materials can be modified but in some cases new methods have to be developed, both of which approaches require underpinning research. Trade in materials is international in nature and therefore it is very important to harmonize national standards and develop truly international standards which will help remove technical barriers to trade. This requires effort at a national level in order to collaborate in the international fora and negotiate from a position of strength. Both producers and users of materials need to become involved in standards-related activities. In underpinning prestandards research VAMAS, the Versailles Project on Advanced Materials, plays an important role and is developing an internationally recognized technical infrastructure from which standards can be developed. This paper discusses the need and scope for international collaboration in standards-related activities. This paper was presented at the National Workshop on Standardization for Advanced Materials, Strategic Issues, a collaborative effort of Bureau of Indian Standards (BIS), National Materials Policy Project (TIFAC/DST) and Confederation of Engineering Industry (CEI).     

A single amino acid change in the acetylcholinesterase-like domain of thyroglobulin causes congenital goiter with hypothyroidism in the cog/cog mouse: a model of human endoplasmic reticulum storage diseases

Newly synthesized thyroglobulin (Tg), the major secretory glycoprotein of the thyroid gland, folds and homodimerizes in the endoplasmic reticulum (ER) before its export to the site of iodination, where it serves as the precursor for thyroid hormone synthesis. In families with defective Tg export, affected individuals suffer from a thyroidal ER storage disease characterized by a distended thyrocyte ER containing misfolded Tg, along with induced ER molecular chaperones. Inherited as an autosomal recessive trait, deficient Tg causes congenital hypothyroidism in newborns that, if untreated, results in goiter along with serious cognitive and growth defects. Recently, a similar phenotype has been observed in inbred cog/cog mice, although the precise molecular defect has remained undefined. Here, we have isolated and cloned a full-length 8.5-kb Tg cDNA from cog/cog mice and unaffected isogenic AKR/J mice. Comparison of the complete sequences reveals that cog/cog mice express a Leu-2263 --> Pro missense mutation in the acetylcholinesterase-homology domain of Tg. Heterologous expression studies in COS cells indicate that cog Tg exhibits a severe defect in exit from the ER. Site-directed mutagenesis of cog Tg to convert the single amino acid back to Leu-2263 restores normal Tg secretion. We conclude that the cog mutation in Tg is responsible for this ER storage disease that causes thyroid dyshormonogenesis.     

In-plane shear behaviour of profiled steel sheeting

This paper will describe the behaviour of profiled steel sheeting under inplane shear and its application in building frames. Analytical models for shear strength and stiffness of the profiled steel sheeting are developed and validated by small scale model tests and finite element analyses. The strength, stiffness, failure modes and strain conditions are found to be greatly influenced by the boundary condition of the sheeting. The values of several factors related to the mode of attachment of the sheeting to practical building frames are studied to verify the suitability of design equations.     

Performance Modeling and Analysis of a Class of ARQ Protocols in Multi-Hop Wireless Networks

This paper models and analyzes the performances of a class of ARQ (automatic repeat request) protocols in a multi-hop wireless data network. The performance metric here is the number of transmissions required for successful delivery of a packet over a multi-hop path. By using a discrete-time Markov model, the distribution for the total required number of transmissions is modeled as phase type distribution. The effects of different network parameters-such as packet error rate in each hop, maximum number of allowable retransmissions at each hop and retransmission probability at each hop-on the required total number of transmissions are investigated. The novelty of this model is that the probability mass function (pmf) for the number of transmissions required for successful end-to-end delivery of a packet can be easily obtained under different hop-level error control policies. Using the pmf, the tradeoff between transmission energy and percentage of data delivery (i.e., reliability) in a multi-hop path can be analyzed. The analytical model is validated by simulations. While the proposed analytical framework is general enough to capture the impact of any MAC (medium access control) mechanism at each hop, we specifically present typical performance results under IEEE 802.11 DCF (distributed coordination function) MAC     

In situ fabricated iodine-adlayer assisted selective electrooxidation of uric acid in alkaline media

This work presents the electrooxidation of uric acid (UA) at an iodine-adlayer-modified gold, Au (I|Au (poly)) electrode in 0.1 M NaOH solution using cyclic voltammetric, amperometric and open-circuit potential measurement techniques. A tremendous enhancement of the electrode activity towards the electrooxidation of UA was achieved by virtue of the simple modification of the Au (poly) electrode surface with a neutral iodine-adlayer, fabricated in situ through the spontaneous oxidative chemisorption of iodide present in the sample solution. The cyclic voltammetric peak current increases remarkably for the oxidation of UA and the peak potential shifts by 365 mV to the negative direction of potential compared to the bare Au (poly) electrode. Oxidation of ascorbic acid (AA) at the I|Au (poly) electrode takes place at the same potential as that at the bare electrode, but the peak current intensity is almost twice at the bare Au (poly) electrode as compared to the modified one. In the mixture of the AA and UA, the cyclic voltammetric signals corresponding to the oxidations of AA and UA were resolved by 340 mV. The electrode response in the mixture was highly reproducible because of the inhibition of adsorption of oxidation products and UA.     

Robust Prewhitening for ICA by Minimizing <Emphasis Type="Italic">β</Emphasis>-Divergence and Its Application to FastICA

Many estimation methods for independent component analysis (ICA) requires prewhitening of observed signals. This paper proposes a new method of prewhitening named β-prewhitening by minimizing the empirical β-divergence over the space of all the Gaussian distributions. The value of the tuning parameter β plays the key role in the performance of our current proposal. An attempt is made to propose an adaptive selection procedure for the tuning parameter β for this algorithm. At last, a measure of performance index is proposed for assessing prewhitening procedures. Simulation results show that β-prewhitening efficiently improves the performance over the standard prewhitening when outliers exist; it keeps equal performance otherwise. Performance of the proposed method is compared with the standard prewhitening by both FastICA and our proposed performance index.     

Ineffectiveness and poor reliability of arsenic removal plants in West Bengal, India

In the recent past, arsenic contamination in groundwater has emerged as an epidemic in different Asian countries, such as Bangladesh, India, and China. Arsenic removal plants (ARP) are one possible option to provide arsenic-safe drinking water. This paper evaluates the efficiency of ARP projects in removing arsenic and iron from raw groundwater, on the basis of our 2-year-long study covering 18 ARPs from 11 manufacturers, both from home and abroad, installed in an arsenic affected area of West Bengal, India, known as the Technology Park Project (TP project). Immediately after installation of ARPs on August 29, 2001, the villagers began using filtered water for drinking and cooking, even though our first analysis on September 13, 2001 found that 10 of 13 ARPs failed to remove arsenic below the WHO provisional guideline value (10 microg/L), while six plants could not achieve the Indian Standard value (50 microg/L). The highest concentration of arsenic in filtered water was observed to be 364 microg/L. Our 2-year study showed that none of the ARPs could maintain arsenic in filtered water below the WHO provisional guideline value and only two could meet the Indian standard value (50 microg/L) throughout. Standard statistical techniques showed that ARPs from the same manufacturers were not equally efficient. Efficiency of the ARPs was evaluated on the basis of point and interval estimates of the proportion of failure. During the study period almost all the ARPs have undergone minor or major modifications to improve their performance, and after our study, 15 (78%) out of 18 ARPs were no longer in use. In this study, we also analyzed urine samples from villagers in the TP project area and found that 82% of the samples contained arsenic above the normal limit.     

Experimental and computational studies of the gas-phase reaction of halon 1211 with hydrogen

The gas-phase reaction of halon 1211 (CBrClF2) with hydrogen has been studied experimentally at atmospheric pressure in a plug flow, isothermal reactor over the temperature range of 673 to 973 K, at residence times ranging from 0.5 to 2.5 s with an input ratio of N2:H2:halon 1211 of 19:10:1. The major carbon containing products include CHClF2, CHBrF2, CH2F2, and CH4. Gas-phase reactions of CHClF2, CCl2F2, and CH2F2 with hydrogen are also investigated under the conditions similar to those for halon 1211 hydrodehalogenation, and the results are used to assist in understanding the mechanism of the reaction of halon 1211 with hydrogen. A kinetic reaction scheme involving 90 species and 430 reaction steps is developed and used to model the halon 1211 hydrodehalogenation reaction. Generally, satisfactory agreement between experimental and computational results is obtained for the production of major species. Using the software package AURORA, the reaction pathways leading to the formation of major products are elucidated. It has been found that the reaction steps involving CF2 are responsible for the formation of CH4.