Enhancement of Heat Transfer in Shell and Tube Heat Exchanger using Different Porous Medium: A CFD-based Study

The present study is to investigate the heat transfer enhancement in a cylindrical heat exchanger using porous media. The heat exchanger is modelled by a cylindrical cavity (Shell) with inlet and outlet thermally insulated ports and five tubes which contain hot water and cold water flows in shell. The effect of porosity on heat transfer enhancement is studied at different mass flow rate 0.15, 0.2, 0.25 and 0.30 Kg/sec. The study about effect of porosity on heat transfer enhancement is done by both experimentally and CFD based and the results are compared with simple heat exchanger. In present study, two different types of porous materials are used and Porosity is taken as 80%. The effect of varying mass flow rate on outlet temperature, heat transfer coefficient, Reynolds number and Nusselt number has been investigated

Family History of Cancer and Tobacco Exposure in Index Cases of Pancreatic Ductal Adenocarcinoma

Aim. To examine interaction between history of cancer in first-degree relatives and tobacco smoking in index patients of pancreatic adenocarcinoma. Methods. We carried out a case-control involving 113 patients with pancreatic adenocarcinoma and 110 controls over a 12-month period at the Freeman Hospital, Newcastle upon Tyne, UK. They were all administered a detailed tobacco exposure questionnaire and a family history questionnaire. We calculated cumulative tobacco exposure and risk for pancreas cancer. Results. Both smokers (OR 3.01 (95% CI: 1.73 to 5.24)) and those with a family history of malignancy (OR 1.98 (95% CI: 1.15–3.38)) were more likely to develop pancreatic cancer. Having more than one first-degree relative with cancer did not significantly further increase the risk of pancreatic cancer. Amongst pancreatic cancer cases, cumulative tobacco exposure was significantly decreased (P = .032) in the group of smokers (current and ex-smokers) who had a family history of malignancy [mean (SD): 30.00 (24.77) pack-years versus 44.69 (28.47) pack-years with no such history]. Conclusions. Individuals with a family history of malignancy are at an increased risk of pancreatic cancer. Furthermore, individuals with a family history of malignancy and who smoke appear to require a lesser degree of tobacco exposure for the development of pancreatic cancer

Statistical analysis of entropy correction from topological defects in Loop Black Holes

In this paper we discuss the entropy of quantum black holes in the LQG formalism when the number of punctures on the horizon is treated as a quantum hair, that is we compute the black hole entropy in the grand canonical (area) ensemble. The entropy is a function of both the average area and the average number of punctures and bears little resemblance to the Bekenstein-Hawking entropy. In the thermodynamic limit, both the "temperature" and the chemical potential can be shown to be functions only of the average area per puncture. At a fixed temperature, the average number of punctures becomes proportional to the average area and we recover the Bekenstein-Hawking area-entropy law to leading order provided that the Barbero-Immirzi parameter, $\gamma$, is appropriately fixed. This also relates the chemical potential to $\gamma$. We obtain a sub-leading correction, which differs in signature from that obtained in the microcanonical and canonical ensembles in its sign but agrees with earlier results in the grand canonical ensemble.Comment: 12 pages, no figures. Version to appear in Phys. Rev.

Classical and quantum: a conflict of interest

We highlight three conflicts between quantum theory and classical general relativity, which make it implausible that a quantum theory of gravity can be arrived at by quantising classical gravity. These conflicts are: quantum nonlocality and space-time structure; the problem of time in quantum theory; and the quantum measurement problem. We explain how these three aspects bear on each other, and how they point towards an underlying noncommutative geometry of space-time.Comment: 15 pages. Published in `Gravity and the quantum' [Essays in honour of Thanu Padmanabhan on the occasion of his sixtieth birthday] Eds. Jasjeet Singh Bagla and Sunu Engineer (Springer, 2017

DFT Study of Planar Boron Sheets: A New Template for Hydrogen Storage

We study the hydrogen storage properties of planar boron sheets and compare them to those of graphene. The binding of molecular hydrogen to the boron sheet (0.05 eV) is stronger than that to graphene. We find that dispersion of alkali metal (AM = Li, Na, and K) atoms onto the boron sheet markedly increases hydrogen binding energies and storage capacities. The unique structure of the boron sheet presents a template for creating a stable lattice of strongly bonded metal atoms with a large nearest neighbor distance. In contrast, AM atoms dispersed on graphene tend to cluster to form a bulk metal. In particular the boron-Li system is found to be a good candidate for hydrogen storage purposes. In the fully loaded case this compound can contain up to 10.7 wt. % molecular hydrogen with an average binding energy of 0.15 eV/H2.Comment: 19 pages, 7 figures, and 3 table

Models of wave-function collapse, underlying theories, and experimental tests

We describe the state of the art in preparing, manipulating and detecting coherent molecular matter. We focus on experimental methods for handling the quantum motion of compound systems from diatomic molecules to clusters or biomolecules.Molecular quantum optics offers many challenges and innovative prospects: already the combination of two atoms into one molecule takes several well-established methods from atomic physics, such as for instance laser cooling, to their limits. The enormous internal complexity that arises when hundreds or thousands of atoms are bound in a single organic molecule, cluster or nanocrystal provides a richness that can only be tackled by combining methods from atomic physics, chemistry, cluster physics, nanotechnology and the life sciences.We review various molecular beam sources and their suitability for matter-wave experiments. We discuss numerous molecular detection schemes and give an overview over diffraction and interference experiments that have already been performed with molecules or clusters.Applications of de Broglie studies with composite systems range from fundamental tests of physics up to quantum-enhanced metrology in physical chemistry, biophysics and the surface sciences.Nanoparticle quantum optics is a growing field, which will intrigue researchers still for many years to come. This review can, therefore, only be a snapshot of a very dynamical process

Bound States of String Networks and D-branes

We show the existence of non-threshold bound states of (p, q) string networks and D3-branes, preserving 1/4 of the full type IIB supersymmetry, interpreted as string networks dissolved in D3-branes. We also write down the expression for the mass density of the system and discuss the extension of the construction to other Dp-branes. Differences in our construction of string networks with the ones interpreted as dyons in N=4 gauge theories are also pointed out.Comment: 11 pages, latex, minor modifications (version to appear in Phys. Rev. Lett.

Report of the Task Force on Enhancing technology use in agriculture insurance

Pradhan Mantri Fasal Bima Yojana (PMFBY) is a flagship scheme of the Government of India to provide insurance coverage and financial support to farmers in the event of failure of any of the notified crops, unsown area and damage to harvest produce as a result of natural calamities, pests and diseases to stabilise the income of farmers, and to encourage them to adopt modern agricultural practices. The scheme is a considerable improvement over all previous insurance schemes in India and is heavily subsidised by the state and central governments. The scheme aims to cover 50 percent of the farming households within next 3 years. During its implementation in the last one season, several challenges relating to enrolment, yield estimation, loss assessment, and claim settlement were reported by farmers, insurance companies as well as the state governments. It was also noted that several technological opportunities existed for possibly leveraging support to the Indian crop insurance program for enhanced efficiency and effectiveness. NITI Aayog of the Government of India, therefore, constituted a Task Force to deliberate on this subject and identify such potential opportunities. This report summarises the recommendations of the Task Force. The Task Force constituted to address the issue of technology support to crop insurance comprised the following 5 sub-groups: (1) Remote Sensing & Drones; (2) Decision Support Systems, Crop Modelling & Integrated Approaches; (3) IT/ICT in Insurance; (4) Crop Cutting Experiments (CCEs); and (5) Technologies for Livestock and Aquaculture Insurance. Each sub-group had several discussions with experts in the respective areas, and submitted draft reports. More than 100 experts related to professional research agencies, insurance industry, banks, and the government contributed to these discussions. Technological options available in the country and abroad were considered by all groups. The Task Force together with the sub-groups then deliberated on key issues and formulated its recommendations as presented in this report. During the discussions it was realised that there were many administrative and institutional issues that needed to be addressed in PMFBY. However, the focus of the Task Force was on its main mandate, technology use in crop insurance. We hope these recommendations would help the Indian crop insurance sector take full advantage of the technological options suggested so as to increase its efficacy and effectiveness leading to reduced agrarian distress in the country