MODELING AND ANALYSIS OF A STAIR CASE LIFT FOR MATERIAL HANDLING SYSTEM

Abstract: This topic deals with the fabrication and analysis of a stair case lift, which can be use as Material Handling System. A stair case lift is a mechanical device for lifting people and wheelchairs up and down on the stairs, who may find difficulty in doing so themselves. For sufficiently wide stairs, a rail is mounted to the treads of the stairs. A chair or lifting platform is attached to the rail. A person on the chair or platform is lifted as the chair or platform moves along the rail, old age and goods are to be carried across the stair case. Stair case lift is a type of lift that can be mounted on the stair case without altering civil structure. This lift runs on electric power and consists of a motor, reduction gear box, rope drive, two rails a sliding chair. In this system we use DC motor for changing the polarity of the power supply which will make the motor run in reverse direction connected with the earlier, while the later will form the entire assembly run to in downward direction, with the help of Toggle switches and push buttons. Advantages over the conventional hydraulic lift are no civil structure and alteration is required, low cost, less bulkiness, less power, less maintenance requires. Easy design, easy installations. Can be of industrial use too. Moreover, considering some drawbacks due to weight carrying capacity completely depend upon the capacity of motor. There is lot of scope for further modification in the project as using monorail instead of two. Use of belt drive or chain drive instead of rope drive. Incorporation and automation/ timer unit which will ease the use of device. Rack and carrier arrangement for using the device for curved stair case. Use of work & roller reduction gear assembly.

Linear stability analysis of a nuclear reactor using the lumped model

The stability analysis of a nuclear reactor is an important aspect in the design and operation of the reactor. A stable neutronic response to perturbations is essential from the safety point of view. In this paper, a general methodology has been developed for the linear stability analysis of nuclear reactors using the lumped reactor model. The reactor kinetics has been modelled using the point kinetics equations and the reactivity feedbacks from fuel, coolant and xenon have been modelled through the appropriate time dependent equations. These governing equations are linearized considering small perturbations in the reactor state around a steady operating point. The characteristic equation of the system is used to establish the stability zone of the reactor considering the reactivity coefficients as parameters. This methodology has been used to identify the stability region of a typical pressurized heavy water reactor. It is shown that the positive reactivity feedback from xenon narrows down the stability region. Further, it is observed that the neutron kinetics parameters (such as the number of delayed neutron precursor groups considered, the neutron generation time, the delayed neutron fractions, etc.) do not have a significant influence on the location of the stability boundary. The stability boundary is largely influenced by the parameters governing the evolution of the fuel and coolant temperature and xenon concentration

Effect of Coolant Inventories and Parallel Loop Interconnections on the Natural Circulation in Various Heat Transport Systems of a Nuclear Power Plant during Station Blackout

Provision of passive means to reactor core decay heat removal enhances the nuclear power plant (NPP) safety and availability. In the earlier Indian pressurised heavy water reactors (IPHWRs), like the 220 MWe and the 540 MWe, crash cooldown from the steam generators (SGs) is resorted to mitigate consequences of station blackout (SBO). In the 700 MWe PHWR currently being designed an additional passive decay heat removal (PDHR) system is also incorporated to condense the steam generated in the boilers during a SBO. The sustainability of natural circulation in the various heat transport systems (i.e., primary heat transport (PHT), SGs, and PDHRs) under station blackout depends on the corresponding system's coolant inventories and the coolant circuit configurations (i.e., parallel paths and interconnections). On the primary side, the interconnection between the two primary loops plays an important role to sustain the natural circulation heat removal. On the secondary side, the steam lines interconnections and the initial inventory in the SGs prior to cooldown, that is, hooking up of the PDHRs are very important. This paper attempts to open up discussions on the concept and the core issues associated with passive systems which can provide continued heat sink during such accident scenarios. The discussions would include the criteria for design, and performance of such concepts already implemented and proposes schemes to be implemented in the proposed 700 MWe IPHWR. The designer feedbacks generated, and critical examination of performance analysis results for the added passive system to the existing generation II & III reactors will help ascertaining that these safety systems/inventories in fact perform in sustaining decay heat removal and augmenting safety

Synthesis of a CFD benchmark exercise based on a test in the PANDA facility addressing the stratification erosion by a vertical jet in presence of a flow obstruction

The benchmark exercise discussed in this paper was conducted within the OECD/NEA project HYMERES. The specific experiment in the PANDA facility chosen for the present benchmark addresses the stratification erosion in a vessel where the upper region contained initially a mixture of steam and helium, and the remaining volume was filled with steam. The mixing is induced by a vertical steam jet, which originates from the exit of a circular pipe located below the bottom of the helium-rich layer. The stratification erosion process is somewhat slowed down by a small circular plate above the jet source. The exercise consisted of a blind phase, and an open phase. Two sets of blind simulations were requested: one set obtained using a “common model”, and a second set produced by a “best estimate” model. For the “common model”, a list of recommendations was given, whereas for the “best estimate” model, each participant was free to choose the modelling approach. The submitted results for the erosion times were in a large band, and especially the large differences in the results with the “common model” were not expected. The results of the best estimate simulations showed that the combination of mesh and modelling approach can lead to a wide spread of results. The most important difficulty in interpreting the results and finding the reason of the large deviations was the lack of information on the velocity field downstream of the obstruction. Therefore, for the open phase extended data from auxiliary, “zero” tests (for similar conditions but without helium layer) were provided to the participants to permit a more basic validation of their models, using a “multi-step approach”. The step-by-step validation permitted some progress with respect to some of the items identified in the blind benchmark. However, large discrepancies with data in the final analyses of the test are observed, which cannot be easily attributed to specific model deficiencies or insufficient detail of the mesh. These results raised some questions in relation to best practice guidelines for the use of Computational Fluid Dynamic (CFD) codes for containment analysis and indicated needs for further CFD-grade experiments

Metal nanoparticles: The protective shield against virus infection.

Re-emergence of resistance in different pathogens including viruses are the major cause of human disease and death, which is posing a serious challenge to the medical, pharmaceutical and biotechnological sectors. Though many efforts have been made to develop drug and vaccines against re-emerging viruses, researchers are continuously engaged in the development of novel, cheap and broad-spectrum antiviral agents, not only to fight against viruses but also to act as a protective shield against pathogens attack. Current advancement in nanotechnology provides a novel platform for the development of potential and effective agents by modifying the materials at nanolevel with remarkable physicochemical properties, high surface area to volume ratio and increased reactivity. Among metal nanoparticles, silver nanoparticles have strong antibacterial, antifungal and antiviral potential to boost the host immunity against pathogen attack. Nevertheless, the interaction of silver nanoparticles with viruses is a largely unexplored field. The present review discusses antiviral activity of the metal nanoparticles, especially the mechanism of action of silver nanoparticles, against different viruses such HSV, HIV, HBV, MPV, RSV, etc. It is also focused on how silver nanoparticles can be used in therapeutics by considering their cytotoxic level, to avoid human and environmental risks