Realistic simulation of a wireless signal propagation in an urban environment

This paper presents results obtained from a 3D ray tracing electromagnetic model designed to map the signals in a high rise environment (urban) within the same floor and at the floors above and below that floor. Apart from using ray tracing, the dielectric properties of the materials from each floor are included to achieve realistic signal profiles. The simulation is done for scenarios based on a single base-station and multiple base-stations on the same floor and multi-floors. We have refined existing indoor propagating model to obtain realistic signal distribution in a high rise building. New model include the dielectric properties of materials exists in real environment. The simulation program is written in Visual C++

Quantitative evaluation of abrasive contamination in ductile material during abrasive water jet machining and minimising with a nozzle head oscillation technique

In the area of grit blasting, it is well known that microscopically small abrasive debris gets trapped on the surface, and due to impact this grit might cause the surface to fracture and a fraction of it to embed. The same problem appears in abrasive aqua jet machining (AAJM), especially in the so-called deformation wear zone or striation zone. An experimental study was undertaken on a commonly used ductile material, aluminium Al-Mg4, 5Mn, which is used as a base material for manufacturing most of the aircraft/aerospace components. The results indicated that as the depth of cut increases the grit contamination decreases. A comparison was made between straight cutting and oscillation cutting, and it was observed that oscillation cutting is 10 times better than straight cutting for ductile material with respect to particle contamination. Alternative technology is suggested to overcome the grit contamination problem. Crwon Copyright © 2004 Published by Elsevier Ltd. All rights reserved.C

Quantitative and comparative study of abrasive contamination in ductile and brittle material for abrasive aqua jet machining (AAJM)

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Automatic generation of global phase equilibrium diagram from equation of state

A computational tool that uses an automated and reliable procedure for systematic generation of global phase equilibrium diagram (GPED) is developed for binary system using equation of state and its extension to the ternary system is discussed. The proposed algorithm can handle solid phase and also can predict all major six types of phase diagrams. The procedure enables automatic generation of GPED which incorporates calculations of all important landmarks such as critical endpoints, quadruple point (if any), critical line, liquid-liquid-vapor line (if any), solid-liquid-liquid line (if any) and solid-liquid-vapor line. The method is also capable of locating all azeotropic phenomena such as azeotropic endpoint, critical azeotrope, pure azeotropic point and azeotropic lines. Although, we demonstrated the methodology for cubic equation of state, the proposed strategy is completely general that doesn\u27t require any knowledge about the type of phase diagram and can be applied to any pressure explicit equation of state model. Newton homotopy based global method has been applied for phase stability test and critical point calculations to ensure reliability. Having computed the binary phase diagrams, the methodology to generate global phase diagrams for ternary system is discussed that can locate all important thermodynamic landmarks such as tricritical point, quadruple critical endpoint, quadruple azeotropic endpoint, quintuple point and critical azeotropic endpoint. The procedure to trace ternary phenomena having two degree of freedom such as critical surface, solid-liquid-vapor surface and liquid-liquid-vapor surface has been discussed. Finally, applications of reliable global methods to solve the fluid-fluid phase equilibrium problem using SAFT equation for binary system and the solid-fluid phase equilibrium problem for binary and ternary systems have been demonstrated through representative computations

Categorisation of failures in telecommunication networks

Traditional techniques and models used to determine the availability and failure rates of telecommunications networks are based on classic failure models such as Mean-time between Failure and Mean-time between Service Outage predictors. Network failures occur for many different reasons and occur in many different forms. These classic models only assume that the failure is caused by a hardware component of the network. With the widespread deployment of Internet technologies other factors that cause or contribute to failure in a telecommunications network must be explored. Two additional failure modes to existing published failure models, failure from Denial of Service Attacks, and failures due to Catastrophic Events have been identified and defined along with an initial outline of a generalized prediction model based on Dynamic System Theory.E

Quantitative study of abrasive contamination in a ductile material during abrasive aqua jet machining

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A study of clinical profile of acute medical illnesses in geriatric patients

Background: Population aging is transforming the world. Elderly people are the most rapidly growing population group worldwide, which eventually include India also. The objective of the study was to provide the health care needs of this growing numbers of the vulnerable heterogeneous population, reliable data are still lacking and with recognition of the need the present study was designed. Materials and methods: A prospective observational study which was conducted at the department of medicine, Civil Hospital, Ahmedabad for the duration of 2 years, in which total 100 patients who was ≥65 years of age with acute emergency illness were included and data were collected. Results: Patients had common symptoms like breathlessness (45%) and giddiness (39%) and commonly encountered clinical conditions were cerebrovascular stroke (31%) and acute LVF (19%). Hypertension was the most common disease associated with CV stroke, acute LVF and IHD. Hypertension (44) and hypertension and diabetes (40) together were the commonly encountered co-morbidities. Most patients with co-morbidities were found complaint to their medicines. Among study participants, 87% of diabetics had also hypertension as compared to 81.5% nondiabetics who were suffering from hypertension. Conclusion: Most common acute medical illness in geriatric population is due to the chronic co-morbid conditions. It is crucial to maintain chronic morbidity in a timely manner to minimize the complication. Post-acute care may be aimed to promote the functional recovery of older adults, prevent unnecessary hospital readmission, and avoid premature admission to a long-term care facility

On network security and internet vulnerability

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Dynamic reconfiguration and graph theory approaches to failures in IT based telecommunication networks

For the last quarter of a century understanding of the nature of telecommunication network traffic has been considered as an important research topic. Any well designed recovery strategy has to take into account the different resilience requirements of the single traffic flows in order to avoid excessive usage of bandwidth for standby links. Faced with multiple recovery options, an internet service provider (ISP) must decide which flows to protect to what extent against networks. Traditional techniques and models used to determine the availability and failure rates of telecommunications networks are based on classic failure models such as Mean-time between failure and Mean-time between service outage predictors. Network failures occur for many different reasons and occur in many different forms. These classic models only assume that the failure is caused by a hardware component of the network. With the widespread deployment of Internet technologies other factors that cause or contribute to failure in a telecommunications network must be explored. Two additional failure modes to existing published failure models, failure from Denial of Service attacks, and failures due to catastrophic events have been identified and defined along with an initial outline of a generalized prediction model based on Dynamic System Theory. Discussion is done on the effects of failures and survivability issues in network failures and how to overcome failures in IT based telecommunication networkE