Integration of product design,process planning,scheduling, and FMS control using XML data representation

An efficient model for communications between CAD, CAPP, and CAM applications in distributed manufacturing planning environment has been seen as key ingredient for CIM. Integration of design model with process and scheduling information in real-time is necessary in order to increase product quality, reduce the cost, and shorten the product manufacturing cycle. This paper describes an approach to integrate key product realization activities using neutral data representation. The representation is based on established standards for product data exchange and serves as a prototype implementation of these standards. The product and process models are based on object-oriented representation of geometry, features, and resulting manufacturing processes. Relationships between objects are explicitly represented in the model (for example, feature precedence relations, process sequences, etc.). The product model is developed using XML-based representation for product data required for process planning and the process model also uses XML representation of data required for scheduling and FMS control. The procedures for writing and parsing XML representations have been developed in object-oriented approach, in such a way that each object from object-oriented model is responsible for storing its own data into XML format. Similar approach is adopted for reading and parsing of the XML model. Parsing is performed by a stack of XML handlers, each corresponding to a particular object in XML hierarchical model. This approach allows for very flexible representation, in such a way that only a portion of the model (for example, only feature data, or only the part of process plan for a single machine) may be stored and successfully parsed into another application. This is very useful approach for direct distributed applications, in which data are passed in the form of XML streams to allow real-time on-line communication. The feasibility of the proposed model is verified in a couple of scenarios for distributed manufacturing planning that involves feature mapping from CAD file, process selection for several part designs integrated with scheduling and simulation of the FMS model using alternative routings.     

Pool Boiling Enhancement through Graphene and Graphene Oxide Coatings

ABSTRACT

Boiling has served as an effective means to dissipate large quantities of heat over small areas. Graphene, a two-dimensional material, has garnered significant attention of researchers due to its excellent thermal properties. In this study, copper test chips are dip coated with a solution consisting of graphene oxide and graphene and its pool boiling performance with distilled water at atmospheric pressure was investigated. The surfaces were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy which confirmed the presence of graphene and graphene oxide. The contact angles measured on the coated surfaces indicated hydrophobic wetting behavior. Four heat transfer surfaces were prepared with dip coating durations of 120 s, 300 s, 600 s, and 1200 s, respectively. A Critical Heat Flux (CHF) of 182 W/cm² and a heat transfer coefficient (HTC) of 96 kW/m²°C was obtained with the shortest coating duration which translated to an enhancement of 42% in CHF and 47% in HTC when compared to a plain uncoated surface under similar conditions. Contact angle changes were not seen to be responsible, although roughness was seen as an influencing factor contributing to the enhancement. Further studies are needed to explain the enhancement mechanism.     

Studies on the effect of hydrogen induction on performance,emission and combustion behaviour of a WCO emulsion based dual fuel engine

This paper aims at studying the effect of hydrogen induction on engine performance, emission and combustion behaviour of a diesel engine fuelled with the emulsion of used palm oil (called as WCO-waste cooking oil) as pilot fuel and hydrogen as primary fuel. A single cylinder water-cooled direct injection diesel engine was tested at 100% and 40% loads. Results were compared with neat diesel, neat WCO and WCO emulsion at both loads in single fuel operation. WCO emulsion in single fuel mode indicated improvement in performance and reduction in all emissions as compared to neat WCO. Dual fuel operation with hydrogen induction further reduced the emissions of smoke HC and CO with WCO as pilot fuel at all power outputs. However, hydrogen induction resulted in reduced thermal efficiency at 40% load. WCO emulsion showed higher ignition delay as compared to neat WCO. Dual fuel operation with hydrogen induction increased the ignition delay further. Heat release pattern showed higher premixed combustion rate with hydrogen induction mainly at high power outputs. Premixed combustion rate became very high at higher rates of hydrogen admission mainly at high power output. In general, hydrogen induction showed superior performance at high power output and inferior performance at low power output with WCO emulsion as injected fuel.     

Enhancement of condensate water quantity and coefficient of performance of an air conditioning system: An experimental study

The objective of the present work is to increase the quantity of condensate water from atmospheric air during the air conditioning (A/C) process by using two techniques: increasing moisture content in atmospheric air by adding steam and passing compressed air instead of atmospheric air, respectively. The experiment was performed with both capillary valve and thermostatic expansion valve operations for assessing the volume flow rates (VFRs) of condensate and coefficient of performance (COP) concerning the air A/C arrangement. The control valve operated for the steam supply case was at half valve opening and one-fourth opening, respectively. The R-22 refrigerant was used in this study. From this study, it was perceived that the condensate water quantity was increased by adding the moisture to the inlet air for the A/C system simultaneously with the usage of compressed air. Furthermore, the COP of the system was also compared to normal atmospheric air admission conditions. The compressed air and steam admission to the A/C system has shown a tremendous increase in COP together with the VFR of the system rather than atmospheric air admission conditions.     

Dynamic Operational Policies in an Automated Warehouse

In this paper we consider the optimal relocation of pallets with a high expectancy of retrieval within each storage rack of an automated warehouse to meet the fluctuating, short-term throughput requirements imposed on the automated storage-retrieval machines. The prepositioning of these pallets closer to the input/output point of each rack during off-peak periods will reduce the expected travel time for the storage/retrieval machines during future peak periods of the planning horizon.

As the model has been abstracted from an actual operating environment, we first describe the environment in which the problem has been posed. We then exploit the special structure of the problem to develop conditions that an optimal relocation policy should satisfy. Based on these optimality conditions, we develop a very efficient optimal relocation algorithm. Finally, we present the performance of several relocation policies in the warehouse studied.     

A Multiscale Morphological Insight into Graphene Based Coatings for Pool Boiling Applications

The application of graphene for pool boiling is an attractive option to facilitate compaction and promote efficient heat removal from high power density devices. In this context, chemical characterization of the depositions achieved through commonly employed coating techniques are an important topic of discussion. A detailed structure-property relationship between the morphologies obtained on the mono and multilayered graphene coatings and their corresponding pool boiling performance quantified by the experimental critical heat fluxes is presented. Three different types of graphene (G) and graphene oxide (GO) substrates are characterized: (i) nanoscale: mono and multilayer samples developed through chemical vapor deposition, (ii) Rochester Institute of Technology (RIT)-G/GO colloid generated through an oxygen embrittlement electrochemical process, and (iii) commercially available chemical vapor deposited (CVD)-G/GO colloid. The morphological features were characterized with scanning electron microscope while X-Ray Diffractometer analysis and Raman spectroscopy were used to examine the ordering and stacking of the sheets that result in the unique structural features. Fourier transform infrared and energy dispersive X-ray spectroscopy were employed to identify the overall compositional characteristics of the coated surfaces. The wettability changes and additional nucleation sites for nanoscale coatings, and multiscale roughness features and ridge microstructures for microscale coatings were identified as enhancement mechanisms.     

200 years to CIM

The evolution of manufacturing technology over the last 200 years is described. The stages identified in this evolution are the English system of manufacture, the American system of manufacture, scientific management, process improvement, numerical control, and computer integrated manufacture (CIM)     

Synthesis,growth, and two-photon absorption induced optical limiting action of cytosinium benzoate single crystal

Two-photon absorption induced optical limiting action was demonstrated in cytosinium benzoate (CB) under nanosecond laser (532 nm, 9 ns, and 10 Hz) excitation. Intensity dependent open aperture Z-scan experiment exposed the presence of reverse saturable absorption ascribed due to sequential two-photon absorption. Initially CB single crystals were grown at room temperature by slow evaporation solution technique. Single crystal XRD shows that CB belongs to monoclinic crystal system with P2₁/c space group. Fourier Transform Infrared spectrum was recorded to identify the presence of functional groups. Thermal studies shows that the crystal is stable upto 168 °C. Vickers microhardness studies confirm that the grown crystal was belongs to soft material category. Etching study shows linear rectangular etch patterns (5 s) and well defined stacking planes (10 s) for water etchant. Optical studies demonstrate that CB crystal possess lower cut-off (287 nm) and moderate linear transmittance in visible region. The optical energy band gap of CB crystal was estimated from photoluminescence studies as 3.1 eV. CB with higher two-photon absorption coefficient (1.26?×?10^–10 m/W) and lower onset limiting threshold (1.92?×?10¹² W/m²) can be a potential candidate for developing laser safety devices under nanosecond green laser excitation regime.

     

Experimental studies on a metal hydride–based single bed sorption cryocooler

The present work deals with the development of a MmNi_4.5Al_0.5‐based single bed sorption precooled Linde‐Hampson cryocooler. The working substance and the precooling refrigerant used in this investigation were hydrogen and liquid nitrogen, respectively. The gaseous hydrogen could be compressed merely in the metal hydride reactor in comparative ease and thus an MmNi_4.5Al_0.5‐based metal hydride reactor was used to develop a single bed sorption compressor. The hydrogen is allowed to compress at two different supply pressures of 5 and 10 bar at a constant absorption temperature of 20°C. Desorption temperatures were varied at 65°C, 75°C, and 80°C. Maximum discharge pressures were obtained at a desorption temperature of 80°C as 21 and 27 bar, respectively. The entire cryocooler was designed, fabricated, and tested on the sorption cryocooler. Furthermore, compressed high‐pressure gaseous hydrogen was allowed to flow in the cryocooler at a flow rate of 40 standard cubic centimeter per minute. The minimum temperatures obtained in the evaporator at discharge pressures of 21 and 27 bar were 111 K and 107 K, respectively.     

Investigation on a diesel engine fueled with hydrogen-compressed natural gas and Kusum seed biodiesel: Performance,combustion, and emission approach

The objective of the present study is to evaluate the performance, combustion, and emission characteristics of a compression-ignition engine using hydrogen-compressed natural gas (HCNG)-enriched Kusum seed biodiesel blend (KSOBD20). The flow rate of HCNG was set at 5, 10, and 15 liters per minute (lpm), and the injection pressure was varied in the range of 180–240 bar. Brake thermal efficiency (BTE) and brake-specific fuel consumption (BSFC) were improved when HCNG was added to the KSOBD20. Combustion characteristics, namely, cylinder pressure (CP) and net heat release rate (NHRR), were also improved. Emissions of carbon monoxide (CO), hydrocarbons (HC), and smoke were also reduced, with the exception of nitrogen oxides (NO_x). The higher injection pressure (240 bar) had a positive effect on operating characteristics. At an injection pressure of 240 bar, for KSOB20 + 15 lpm HCNG, the highest BTE and the lowest BSFC were found to be 32.09% and 0.227 kg/kWh, respectively. Also, the CP and NHRR were 69.34 bar and 66.04 J/deg. CO, HC, and smoke levels were finally reduced to 0.013%, 47 ppm, and 9%, respectively, with increased NO_x levels of 1623 ppm. For optimum results in terms of engine characteristics, the fuel combination KSOBD20 + 15 lpm HCNG at fuel injection pressure 240 bar is recommended. Thus, HCNG-enriched KSOBD20 can be used as an alternative fuel in diesel engines without requiring any modifications to increase performance and reduce emissions.