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Effect of varying laser pulse parameters in laser direct metal deposition (LDMD) of Inconel 718 and Ti-6Al-4V have been shown to be quite complex and results in generation of two brittle phases Ti2Ni and TiNi3. Previous experimental study carried out by the authors discussed by Shah et al. (Sci World J 2014:6, 2014) the LDMD of Inconel 718 and Ti-6Al-4V, where all the sample developed cracks except with ones at low powder feed rate. In order to understand the effect of thermal and structural history on development of stresses during LDMD process, an extensive numerical modelling study has been carried out in the work. Thermal and structural analysis results are verified using the available experimental data. Residual stresses are calculated using numerical modelling in the clad region and at the interface of clad and substrate. Experimental and modelling results show that powder mass flow rate plays an important role in crack development during deposition of Inconel 718 and Ti-6Al-4V and it should be kept at minimum level in order to deposit crack-free samples.

Quartz Tuning Fork (QTF) based sensors are used for Scanning Probe Microscopes (SPM), in particular for near-field scanning optical microscopy. Highly sharp Tungsten (W) tips with larger cone angles and less tip diameter are critical for SPM instead of platinum and iridium (Pt/Ir) tips due to their high-quality factor, conductivity, mechanical stability, durability and production at low cost. Tungsten is chosen for its ease of electrochemical etching, yielding high-aspect ratio, sharp tips with tens of nanometer end diameters, while using simple etching circuits and basic electrolyte chemistry. Moreover, the resolution of the SPM images is observed to be associated with the cone angle of the SPM tip, therefore Atomic-Resolution Imaging is obtained with greater cone angles. Here, the goal is to chemically etch W to the smallest possible tip apex diameters. Tips with greater cone angles are produced by the custom etching procedures, which have proved superior in producing high quality tips. Though various methods are developed for the electrochemical etching of W wire, with a range of applications from scanning tunneling microscopy (SPM) to electron sources of scanning electron microscopes, but the basic chemical etching methods need to be optimized for reproducibility, controlling cone angle and tip sharpness that causes problems for the end users. In this research work, comprehensive experiments are carried out for the production of tips from 0.4 mm tungsten wire by three different electrochemical etching techniques, that is, Alternating Current (AC) etching, Meniscus etching and Direct Current (DC) etching. Consequently, sharp and high cone angle tips are obtained with required properties where the results of the W etching are analyzed, with optical microscope, and then with field emission scanning electron microscopy (FE-SEM). Similarly, effects of varying applied voltages and concentration of NaOH solution with comparison among the produced tips are investigated by measuring their cone angle and tip diameter. Moreover, oxidation and impurities, that is, removal of contamination and etching parameters are also studied in this research work. A method has been tested to minimize the oxidation on the surface and the tips were characterized with scanning electron microscope (SEM).

This study focuses on simplification of the Petri net model of a manufacturing system for reduction in the total number of elementary circuits to decrease the analysis time of systems during investigations. A flexible manufacturing system with a tool sharing environment has been developed and investigated using colored Petri nets. The proposed model is extended and implemented on large flexible manufacturing systems (FMSs) having multiple machines and tools. The main objective of this study is to reduce the resultant invariants, as the addition of parts, machines, and tools in black token Petri net models exponentially increases the resultant invariants. Various scenarios have been investigated and compared using the developed model. The structure of the developed colored Petri net (CPN) model allows grouping of the tools that reduces the total number of places in the model. Therefore, it is evident that the developed CPN model reduces the resultant invariant that results in reduced complexity of the system.

Laser direct metal deposition (LDMD) has developed from a prototyping to a single and multiple metals manufacturing technique. It offers an opportunity to produce graded components, with differing elemental composition, phase and microstructure at different locations. In this work, continuously graded Stainless Steel 316L and Inconel 718 thin wall structures made by direct laser metal deposition process have been explored. The paper considers the effects of process parameters including laser power levels and powder mass flow rates of SS316L and Inconel 718 during the deposition of the Steel–Ni graded structures. Microstructure characterisation and phase identification are performed by optical microscopy and X-ray diffraction techniques. Mechanical testing, using methods such as hardness, wear resistance and tensile testing have been carried out on the structures. XRD results show the presence of the NbC and Fe2Nb phases formed during the deposition. The effect of experimental parameters on the microstructure and physical properties are determined and discussed. Work shows that mechanical properties can be controlled by input parameters and generation of carbides provides an opportunity to selectively control the hardness and wear resistance of the functionally graded material.

PurposeA major factor to the success of flexible manufacturing systems (FMSs) is their ability to transport work pieces between different workstations. FMS have now become more advanced and material‐handling systems have become progressively more sophisticated, it is not exceptional to have automated steering of tools to workstations as well. Such system design will improve the tool‐handling capability and the system productivity while holding tool cost to a minimum. Tool cost could represent as much as 25 percent of the operating cost. The purpose of this paper is to propose a new colored Petri net (CPN)‐based approach to the design and development of a tool sharing control system that is intended to help use of the proper and minimal number of tools for a manufacturing system.Design/methodology/approachA new black token timed PN model is first developed, to reduce the complexity of the graphical representation a new CPN model is developed. The new CPN model also allows to find the optimal sequence. The optimal sequence has no effect on the work in process (WIP) but it influences the number of tools used in the system. The main input to the PN model for a manufacturing system is the process plan. Next, all the invariants and total number of possible elementary circuits are determined using the Integrated Net Analyzer (INA) software. Output from the INA software is exported to the Excel spreadsheet. The Excel spreadsheet can be designed to calculate the total number of tokens, processing time, cycle time, etc. of each elementary circuit. Subsequently, the constraints used in Lingo will be created according to critical circuit rules. Finally, linear programming (LP) technique is used to optimize the WIP and tool inventory. Lingo software is used for the LP, the constraints from the Excel sheet will be the input data to the Lingo program, and based on those constraints the Lingo will provide the optimal values for the desired parameters. The output from Lingo will be used to recalculate the cycle time of each elementary circuit in the Excel sheet. The system is then analyzed before and after the implementation of the CPN model.FindingsA new CPN model based on tool‐sharing philosophy for an FMS with N part types and M stations is proposed.Originality/valueThe paper presents a new CPN‐based approach to the design and development of a tool sharing control system, that is, intended to help use of the proper and minimal number of tools for a manufacturing system. The new CPN model also allows to find the optimal sequence. The idea is new and pure and has not been presented before using the methodology adopted in this paper.

Historically, knowledge and skill were of prime focus in medical education, where as professionalism was perceived as an attribute to be acquired during their MBBS studies. In the past decade, trends have changed and graduating medical students are expected to competently deliver care in a professional manner. The selection of applicants with professional attributes at the time of admission is a stepping stone for the formation of a good doctor. This study was conducted to determine the students' and faculty's perception about aptitude of professionalism in the admission process in our setting.In this descriptive cross-sectional study an interactive/scenario-based conversation regarding institutional values, contribute to personal reflection of what will be expected of them in the medical profession and inclusion of such discussion in admission process was made to assess the aptitude of Professionalism of 100 students and 100 faculty members of Avicenna Medical College Lahore. After this conversation the questionnaires were filled by both the groups to record their responses on the aptitude of professionalism. The data was analysed to determine the response patterns of both the groups by using Pearson Chi-Square analysis through crosstabs. All analyses were carried out using SPSS-18.The response of students to professionalism discussion was more positively influenced (91%) compared to the faculty (59%), (p0.05). The students agreed that such scenarios do indicate what our institution values in its students and contribute to personal reflection of what will be expected of them in the medical profession. However, faculty agreed more (85%) than the students (67%) for inclusion of such scenarios in admission process, p0.05.Medical Colleges should include some form of assessment regarding aptitude of professionalism in the admission process to identify future medical students' capacity for professional behaviour. Future studies are needed to determine innovative interview strategies for this purpose.

Laser direct metal deposition (LDMD) has developed from a prototyping to a single metal manufacturing tool. Its potential for creating multimaterial and functionally graded structures is now beginning to be explored. This work is a first part of a study in which a single layer of Inconel 718 is deposited on Ti-6Al-4V substrate. Single layer tracks were built at a range of powder mass flow rates using a coaxial nozzle and 1.5 kW diode laser operating in both continuous and pulsed beam modes. This part of the study focused on the experimental findings during the deposition of Inconel 718 powder on Ti-6Al-4V substrate. Scanning electron microscopy (SEM) and X-ray diffraction analysis were performed for characterization and phase identification. Residual stress measurement had been carried out to ascertain the effects of laser pulse parameters on the crack development during the deposition process.

Wireless sensor networks have several applications of direct and indirect benefit to humanity. These applications can be further enhanced by integrating local wireless sensor networks, internet and cloud technology for storing sensors' data. Our proposed application is based on the same concept. The existing processes of collection and analysis of patients' information requires a lot of effort and additionally they are prone to errors and unnecessary delays in real time information accessibility. These issues limit monitoring and diagnostic capabilities to clinics and hospital only. Wireless sensors provide the capability of information exchange among interconnected on-hand health monitoring equipments. The introduction of this concept is based on wireless sensor networks and utility computing. The information can be stored on “cloud” which will be accessible to medical staff. The proof-of-concept aim is to integrate commodity computing to predecessor medical devices, which should ensure simple integration and cost effectiveness into introduction of a system for health monitoring in remote areas for the best benefit of humanity.