Adenocarcinoma of distal esophagus and gastroesophageal junction: long-term results of surgical treatment in a North Indian Center

This retrospective study reports our experience managing 78 patients with adenocarcinoma of the esophagus and gastroesophageal junction operated between January 1982 and December 1996. Altogether 18 patients presented with stage I and II disease, and 60 patients had stage III and IV disease at presentation; 56 patients (71.8%) were found to have resectable disease. Of these, transhiatal esophagectomy was possible in 51 patients. Transthoracic esophagectomy was done in 3 patients, and a left thoracoabdominal approach was used in 2 patients. The stomach was used as conduit in 50 patients and the colon in 6 patients. Twenty-two patients were found to have unresectable lesions at laparotomy and underwent various palliative procedures. Overall operative mortality was 6.3%. Mortality in the resectable group was only 3.6%. Follow-up ranges from 3 to 128 months, with four patients lost to follow-up at 1, 6, 8, and 10 months. The 5-year survival of the whole group according to Kaplan and Meier survival analysis was 21.27% with a median survival of 13.48 months. Univariate analysis using the log-rank test revealed stage of the disease and resectability to be significant predictors of survival. On multivariate analysis, curative resection appeared to be the most significant predictor of survival in patients undergoing resection.     

Production and Maintenance Planning for Electricity Generators: Modeling and Application to Indian Power Systems

This paper describes the development of an optimization model to perform the fuel supply, electricity generation, generator maintenance, and inter-regional transmission planning for the Northern Regional Electricity Board (NREB) of India. A review of the existing planning process of NREB revealed several areas of potential improvement. In the past, NREB did not use optimization and/or probabilistic methods in their planning. Their decision-making on maintenance, generation and fuel allocation was being performed in a sequential and 'fragmented' fashion, ignoring the possibility of interaction between the generation, transmission, and fuel supply subsystems. The deterministic treatment of outages of generators, and the planning criterion of spreading demand shortfall uniformly across the regions, were other areas of potential improvement. An integrated model, using linear programming together with a heuristic, has been developed to perform joint decision-making on fuel supply, maintenance, generation, and transmission. Monte Carlo simulation is used to incorporate the random outages of generators. The model has been prototyped using GAMS language together with a spreadsheet interface, and implemented for the NREB system. Substantial reduction in system costs is envisaged based on the results of a case study. The model is expected to aid the complex decision-making process of NREB planning engineers in several important ways.     

Improved integrity assessment equations of pipe bends

Pipe bend or elbow is one of the important components in any piping system. Accurate integrity assessment of these pipe bends is very important for reliable operation of all types of plants including nuclear plants. While considerable research has been done in the last few decades to develop accurate integrity assessment procedures of straight pipe with or without cracks, similar efforts were missing for pipe bend or elbow. Reactor Safety Division, Bhabha Atomic Research Centre in collaboration with MPA, University of Stuttgart had embarked upon a comprehensive component integrity test program (CITP) in around 1998 to develop improved integrity assessment methods of piping components in general and elbow in particular. As a part of this program, detailed analytical, numerical and experimental investigations for so many years have generated large number of new equations for improved integrity assessment of elbows. Mainly three aspects of the integrity assessment procedure are focused – development of improved plastic collapse moment equations, proposing new elastic–plastic J-integral and crack opening displacement (COD) estimation schemes to simplify leak-before-break (LBB) analysis and presenting new eta and gamma expressions to evaluate J–R curve from test data. All these newly proposed equations have been validated with the findings of the test data, generated as a part of the CITP. A reasonably good to excellent matching between predictions of the newly proposed equations and test results have been observed in all the cases. The present paper enumerates these research findings in a consolidated yet brief manner.     

Electron beam modification of thermoplastic elastomeric blends made from polyolefins

Thermoplastic elastomeric films have been prepared from blends of ethylene vinylacetate copolymer (EVA) with low-density polyethylene (LDPE), high-density polyethylene (HDPE) and polypropylene (PP) by electron beam modification in presence of radiation sensitizer. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) have been used to evaluate the structural changes of these blends. Scanning electron microscopy (SEM) indicates the morphological features of the blends. Significant improvements of mechanical, dynamic mechanical and set properties have been obtained by electron beam modification of the blends of EVA with LDPE and HDPE. However, in the case of EVA/PP, degradation of the PP phase has been observed. The effects of ditrimethylol propane tetraacrylate (DTMPTA) as radiation sensitizer have also been evaluated from the mechanical and dynamic mechanical properties.     

Effect of process parameters and soy flour concentration on quality attributes and microstructural changes in ready-to-eat potato-soy snack using high-temperature short time air puffing

High-temperature short time (HTST) air puffing has been found to be very useful process for production of potato-soy ready-to-eat snack food as it ideally produced highly porous and light texture. The process parameters considered viz. puffing temperature (185-255 °C) and puffing time (20-60 s) with constant initial moisture content of 36.74% and air velocity of 3.99 m/s for potato-soy blend with varying soy flour content from 5% to 25% were investigated using response surface methodology with central composite rotatable design (CCRD). The optimum product in terms of maximum expansion ratio (3.69), minimum hardness (2754.3 g) and maximum overall acceptability (7.3) were obtained with 10.31% soy flour blend in potato flour at the process conditions of puffing temperature (230.06 °C) and puffing time (25.46 s). Microstructural changes were evaluated at different stages (with an interval of 5 s) of HTST puffing for product obtained with the optimum processing conditions. The maximum expanded porous structures with larger cracks and smaller pits were recorded in the SEM micrographs at 20 s of HTST air puffing.     

Impact of carbon cost on wholesale electricity price: A note on price pass-through issues

Carbon costs – either in the form of a carbon tax or through permit prices in an emissions trading scheme – would ultimately be reflected in higher electricity prices. Carbon cost “pass-through” is critical to the survival of existing coal generation assets and has been discussed widely as a measure of business impact in the electricity industry. This paper sets out in a structured way the factors that determine price pass-through and why this may differ greatly across different systems. Although the basic concept of price pass-through is simple, a clear understanding of the underlying factors is critical to developing insights on how carbon cost would impact on existing coal generation businesses. It is shown that pass-through can vary drastically if the underlying dispatch potential of generators varies significantly across alternative emissions reduction scenarios. It can also vary depending on the availability of competing cleaner forms of generation. Pass-through as a measure of business performance is, therefore, hard to generalize across different circumstances and should be interpreted carefully.     

Studies on hot rolled galvanized steel sheets: Effect of reheating on galvanizing

Galvanized hot rolled steel sheets are inferior to cold rolled sheets because of the segregation of carbides at the surface/sub-surface region. In order to change the distribution of the carbides at the surface/sub-surface region, continuous annealing/reheating operation is carried out at different temperatures prior to the galvanizing operation. The reheating temperature maintained in continuous annealing line is the main factor which redistributes the carbides at the surface/sub-surface region. At intercritical annealing temperature all the carbides get dissolved into the matrix and the surface became suitable for galvanizing reaction. The reducing atmosphere also plays an important role to remove all the room temperature oxides present at the surface. Thus, a combination of proper temperature and reducing atmosphere leads to the proper galvanizing on the hot rolled steel surface.     

Highly regular, modular, and cascadable design of cellularautomata-based pattern classifier

This paper enumerates a new approach to the solution of classification problems based on the properties of Additive Cellular Automata. Classification problem plays a major role in various fields of computer science, such as grouping of the records in database systems, detection of faults in VLSI circuits, image processing, and so on. The state-transition graph of Non-group Cellular Automata (CA) consists of a set of disjoint trees rooted at some cyclic states of unit cycle length - thus forming a natural classifier. First a scheme of classifying the patterns distributed into only two classes has been dealt with. This has been further extended for solution of the multiclass classification problem. The Multiclass Classifier saves on an average 34% of memory as compared to the straight-forward approach storing directly the class of each pattern. A regular, modular, and cascadable hardware implementation of the classifier has been presented which is highly suitable for VLSI realization. The design has been specified in Verilog and verified for functional correctness     

A Low Noise NbTiN-Based 850 GHz SIS Receiver for the Caltech Submillimeter Observatory

We have developed a niobium titanium nitride (NbTiN) based superconductor-insulator-superconductor (SIS) receiver to cover the 350 micron atmospheric window. This frequency band lies entirely above the energy gap of niobium (700 GHz), a commonly used SIS superconductor. The instrument uses an open structure twin-slot SIS mixer that consists of two Nb/AlN/NbTiN tunnel junctions, NbTiN thin-film microstrip tuning elements, and a NbTiN ground plane. The optical configuration is very similar to the 850 GHz waveguide receiver that was installed at the Caltech Submillimeter Observatory (CSO) in 1997. To minimize front-end loss, we employed reflecting optics and a cooled beamsplitter at 4 K. The instrument has an uncorrected receiver noise temperature of 205K DSB at 800 GHz and 410K DSB at 900 GHz. The degradation in receiver sensitivity with frequency is primarily due to an increase in the mixer conversion loss, which is attributed to the mismatch between the SIS junction and the twin-slot antenna impedance. The overall system performance has been confirmed through its use at the telescope to detect a wealth of new spectroscopic lines.