Recognition of undercut features and parting surface of moulded parts using polyhedron face adjacency graph

An injection or die-casting mould is an assembly of parts containing an impression into which molten material is injected. In this article, the undercuts present in mould parts are divided into basically two parts: completely visible and partially visible. A graph-based approach is proposed to identify these undercuts even for the free form objects. Unlike conventional graph based methods a new polyhedron face adjacency graph (PFAG) is proposed with the key concept of visibility of undercuts by using Bezier surface. A rule-based approach is also discussed to automatically generate an optimal parting surfaceof irregular moulded parts. Since the generation of parting surface plays an important and effective role in mould – die design, thus it is essential to develop a simple and robust algorithm based on proposed methodology, which can effectively tackle the problem. Different case studies show that the proposed method can recognize various undercut features without much difficulty.     

Low Cost Communication for High Speed Railway

Wireless Personal Communications - The demand for wireless communication has widely increased in high-speed railway (HSR). The people demand high capacity and efficient communication independent of...     

Controlling unresponsive connections in an active network architecture

This paper presents the design, implementation and evaluation of Limiting Greedy Connections (LGC), an active mechanism for controlling unresponsive connections and minimizing the degradation in network performance caused by bandwidth‐greedy applications. The primary objectives of the LGC mechanism are to limit the impact of greedy connections on a congested node, to keep a loose upper bound on the packet queue occupancy at the intermediate nodes of the network and to minimize packet loss. The LGC mechanism is evaluated for a variety of network topologies, transmitting sources and node queue parameters, using a Java‐based active network testbed. Copyright © 2003 John Wiley &Sons, Ltd.     

Bonding of metal-free phthalocyanine to TiO2(1 1 0) single crystal

The metal-free phthalocyanine interface formation on rutile TiO₂(1 1 0) is investigated using scanning tunneling microscopy and photoelectron spectroscopy. The molecules are adsorbed flat on the surface, centered on the substrate oxygen rows. High-resolution core-level C1s spectroscopy indicates a strong difference between the second layer and the first monolayer bonding to the surface. The C1s core-level from the second layer has a bulk-like line shape whereas the first layer shows a strongly modified line profile. Upon thermal treatment, changes in the N1s core level line profile points to dehydrogenation of the center of the molecule.     

Synthesis of fluorescence poly(N-vinylpyrrolidone) via click chemistry using azide-terminated xanthate mediator (S)-2-(4-azidobutyl propionate)-(O-ethyl xanthate)

Azide-terminated xanthate RAFT agent (S)-2-(4-azidobutyl propionate)-(O-ethyl xanthate) has been synthesized and used for the controlled radical polymerization of N-vinylpyrrolidone (NVP). Kinetics study showed the pesudo first-order kinetics along with gradual increase in molecular weight (M_n) of the resulted polymer up to 69% conversion. Chain-end analysis of the resulted polymer by ¹H NMR showed the presence of the fragments of xanthate mediator at both chain ends. Successful chain extension has also been performed via the click reaction of alkyne-terminated PNVP with azide-terminated PNVP. Moreover, fluorescence pyrene-tagged PNVP has successfully been made via the click reaction of alkyne-functionalized pyrene with azide-terminated PNVP.     

GATE Teamware: a web-based, collaborative text annotation framework

This paper presents GATE Teamware—an open-source, web-based, collaborative text annotation framework. It enables users to carry out complex corpus annotation projects, involving distributed annotator teams. Different user roles are provided (annotator, manager, administrator) with customisable user interface functionalities, in order to support the complex workflows and user interactions that occur in corpus annotation projects. Documents may be pre-processed automatically, so that human annotators can begin with text that has already been pre-annotated and thus making them more efficient. The user interface is simple to learn, aimed at non-experts, and runs in an ordinary web browser, without need of additional software installation. GATE Teamware has been evaluated through the creation of several gold standard corpora and internal projects, as well as through external evaluation in commercial and EU text annotation projects. It is available as on-demand service on GateCloud.net, as well as open-source for self-installation.     

Tuned liquid dampers for multi-storey structure: numerical simulation using a partitioned FSI algorithm and experimental validation

Wind-induced and earthquake-induced vibrations of structures such as super-tall towers and bridges can be efficaciously controlled by tuned liquid dampers (TLDs). This work presents a numerical simulation procedure to study the performance of TLDs–structure system through sigma (\( \sigma \))-transformation-based fluid–structure coupled solver. For this, a ‘C’-based computational code has been developed. The structural equations, which are coupled with the fluid equations in order to achieve the transfer of sloshing forces to structure for damping, are solved by the fourth-order Runge–Kutta method, while the fluid equations are solved using finite-difference-based sigma-transformed algorithm. Different iterative and error schemes are used to optimize the code for larger convergence rate and higher accuracy. For validation, a few experiments are conducted with a three-storey structure using TLDs arrangement. The present numerical results of response of TLD-installed structures match well with the experimental results. The minimum displacement of structure is observed when the resonance condition of the coupled system is achieved through proper tuning of TLDs. Since real-time excitations are random in nature, the performance study of TLDs under random excitation has also been carried out in which the Bretschneider spectrum is used to generate the random input wave.     

Analysis of gap-free chlorophyll-a data from MODIS in Arabian Sea,reconstructed using DINEOF

ABSTRACT

The chlorophyll-a concentration (chl-a), which is an index of phytoplankton pigment present in the oceans, is considered as a key indicator of health of marine ecosystems that could have direct effect on the human life. In this study, spatial and temporal variability of chl-a in the Arabian Sea (AS) is examined using reconstructed cloud-free ocean colour data for the period 2002–2015. Data Interpolating Empirical Orthogonal Function method is used to reconstruct the missing data. Subsequently, wavelet analysis is applied on the reconstructed data to assess the temporal variability in terms of seasonal, intra-seasonal, and interannual variability of chl-a in the AS. Wavelet analysis clearly depicted the low-frequency, stationary modes or approximation levels inferring the monthly, seasonal, and annual mean of the signal, while the high-frequency, non-stationary modes indicated the local abnormalities. From the analysis of gap-free data, the presence of biennial mode of variability in the northern AS chl-a is observed. The analysis further showed the existence of intra-seasonal oscillations in the northern AS during summer monsoon and single dominant peak during winter monsoon. Chl-a appeared to decline slightly during the entire study period across all the selected regions of the AS. Also, it is observed that chl-a in the northwestern region is highly dynamic than in the other regions of the AS.     

Sub-zero Temperature Dependence of Tensile Response of Friction Stir Welded Al-Cu-Li (AA2198) Alloy

Mechanical properties at ambient and cryogenic temperatures of Al-Cu-Li alloy are required for design and fabrication of liquid hydrogen and liquid oxygen tanks of satellite launch vehicles. In the present work, bead-on-sheet, friction stir welding was carried out with three different rotation speeds. The yield and strain hardening behaviors of the welds were evaluated in temperature range of 20 K to 298 K. Both yield stress and strain hardening ability in the specimen increased with decrease in testing temperature. The dependence of yield stress on temperature was modeled on the basis of thermally activated dislocation mobility, while that of strain hardening was modeled on the temperature dependence of dynamic recovery rate parameter. The recovery parameter followed an Arrhenius-type relationship with temperature. The model parameters determined from the experimental data were further used to simulate the stress–strain curves at different sub-zero temperatures for the friction stir welds.