Evaluating part designs for automatic feeding in robotic assembly systems: A geometric analysis of the nesting of polyhedral objects

One of the problems encountered by automatic feeding devices, such as vibratory bowl feeders, in robotic assembly systems is nesting which leads to inseparability of parts and jamming. In this paper, we describe a design evaluation procedure to determine whether a part is prone to nesting and to quantify the degree of nesting. The proposed methodology reduces the 3-D protrusion-hole polyhedral containment problem of nesting to a 2-D polygon containment problem by employing a loop-based feature recognition scheme. Subsequently, the 3-D containment configuration is reconstructed from that of the 2-D by using a strategy calleddrop, pull and push. In this context, we introduce the notion of axis as a characteristic direction of a feature that facilitates the analysis of generalized 3-D polyhedral containment. The algorithms are applicable to generic B-Rep CAD data, and their time and space complexities are polynomial.     

Adaptive epileptic seizure prediction system

Current epileptic seizure "prediction" algorithms are generally based on the knowledge of seizure occurring time and analyze the electroencephalogram (EEG) recordings retrospectively. It is then obvious that, although these analyses provide evidence of brain activity changes prior to epileptic seizures, they cannot be applied to develop implantable devices for diagnostic and therapeutic purposes. In this paper, we describe an adaptive procedure to prospectively analyze continuous, long-term EEG recordings when only the occurring time of the first seizure is known. The algorithm is based on the convergence and divergence of short-term maximum Lyapunov exponents (STLmax) among critical electrode sites selected adaptively. A warning of an impending seizure is then issued. Global optimization techniques are applied for selecting the critical groups of electrode sites. The adaptive seizure prediction algorithm (ASPA) was tested in continuous 0.76 to 5.84 days intracranial EEG recordings from a group of five patients with refractory temporal lobe epilepsy. A fixed parameter setting applied to all cases predicted 82% of seizures with a false prediction rate of 0.16/h. Seizure warnings occurred an average of 71.7 min before ictal onset. Similar results were produced by dividing the available EEG recordings into half training and testing portions. Optimizing the parameters for individual patients improved sensitivity (84% overall) and reduced false prediction rate (0.12/h overall). These results indicate that ASPA can be applied to implantable devices for diagnostic and therapeutic purposes.     

Reduced state correlations of the enskog modulus for gases and liquids

The Enskog modulus, bρ x, has been subjected to a generalized treatment to develop reduced state correlations for nonpolar and polar substances that exhibit hydrogen bonding. These correlations present relationships between 1 + bρx and ρ_R, the reduced density. For nonpolar substances, the PVT data of argon, nitrogen, methane, ethane, and carbon dioxide were used for the development of these relationships, which were found to depend on z_c, the critical compressibility factor. PVT data for ammonia, methyl alcohol, and water yielded a different correlation, which is applicable to polar substances which exhibit hydrogen bonding. These relationships were found to depend on the parameter, β = (T_b-T_m)/M, which quantitatively describes the extent of hydrogen bonding for polar compounds.     

Computer-Aided Process Planning for CNC Pumped-Concrete Placement

Computer-aided process planning (CAPP) is a key step in the integration of computer-aided design and computer-aided construction. The focus of our research is on the development of a CAPP system that will enable automated placement (i.e., pouring) of pumped concrete on a structural floor using computer numerically controlled (CNC) equipment. In this paper we describe the algorithms and methodologies comprising the CAPP system, including (1) algorithms for geometric reasoning (with the CAD model of a given floor) to recognize areas to be concreted and to extract features (such as elevator shafts) that are to be avoided during concrete placement and (2) combinatorial optimization procedures for identification of an efficient sequence of floor slabs to be concreted and the generation of a corresponding area-covering, obstacle-avoiding path plan for the pumped-concrete placement pipe.     

Cutting-tool management in computer-integrated manufacturing

The problem of cutting tool management has been brought to the forefront with the emergence of computer-integrated manufacturing (CIM) and, in particular, flexible manufacturing systems (FMSs). The financial and operational ramifications of effective tool management has spurred considerable research in this area during the past decade and many researchers are proposing sound solutions to various facets of this broad-ranging and difficult problem. This paper identifies critical areas of research for the development of tool management systems in CIM. To develop a framework for this, the paper examines and categorizes work in academia and in industry on the management of cutting-tools in CIM and describes some key implementations, particularly in the metal-cutting industry. The solution of manufacturing problems generally demands an eclectic approach, and for this reason, we have tried to taxonomize, describe, and critique the various research thrusts in an attempt to provide a synthesis of use in more unified approaches.     

Oxidation of sulphide in kraft black liquor and green liquor by residual oxygen in flue gas during precarbonation

Kraft black liquor/green liquor was continuously recirculated in a column (diameter 100 mm, height 450 mm) packed with 16-mm polypropylene Pall rings countercurrent to a gas stream containing N2 and O2 (O2–3.7%). The concentration of sulphide in the green liquor was not affected by oxygen in the gas; the latter, however, completely oxidised the sulphide in kraft black liquor over an 8 h recirculation period.     

Renewable energy scenario in Telangana

ABSTRACT

This article presents an analysis of the current situation of renewable energy in Telangana, India, and predicts the future of renewable energy resources in the state. In India, maximum power is generated using conventional energy sources such as coal and mineral oil. They highly pollute the atmosphere. If new power plants are to be set up, then the import of highly volatile fossil fuels is inevitable. Though nuclear energy is a good alternative to reduce fossil fuel consumption, it is equally hazardous to human life. Hence, the energy world should think of judicious use of renewable energy resources such as solar, wind, ocean, biomass, and geothermal energy. The R&D activities carried out in India in the past three decades have shown good progress in finding a feasible solution to the problem of searching new renewable energy resources. Telangana is the state committed to use the renewable resources in a better way to fulfil its electrical energy needs. This article also analyses the current energy needs of the state and forecasts energy consumption and production in the future with the aim of finding whether the state can continue on the path of development and augment its renewable energy resources.     

Performance Analysis of Auction-Based Distributed Shop-Floor Control Schemes from the Perspective of the Communication System

A growing level of interest in academia and industry centers on the paradigm of distributed shop-floor control in which task and resource allocation in the manufacturing system is accomplished in a distributed manner through message passing and auction-based decision making among autonomous entities. Due to the prominent role played by the communication system in this paradigm, it is important to consider the requirements and performance characteristics of the communication system during the design and evaluation of distributed shop-floor control schemes. In this paper, we propose a two-phase methodology for analyzing auction-based shop-floor control schemes from the perspective of the communication system. In the first phase, the control scheme is modeled as a closed queueing network and performance measures related to the auctioning process and the communication system are obtained rapidly using asymptotic bounding analysis and mean value analysis. Control schemes identified as attractive in the first phase are then evaluated in greater detail during the second phase, using a discrete event simulation model. We illustrate this methodology using two-class and four-class control schemes and discuss insights learned about the impact of various control-scheme-related factors on the performance of the auctioning process and the communication system.     

Computer-integrated collaborative design and operation in the construction industry

The construction industry is emerging as the next frontier for computer-integrated technologies, just as the manufacturing industry did 25 years ago. More recently, the emergence of Internet–Intranet technologies is creating new mechanisms for collaborative design and operation that were previously impossible. The advances that have occurred in the manufacturing industry in the areas of collaborative design, intelligent process planning and computer-integrated manufacturing provide significant insights for formulating analogous paradigms for computer-integrated construction. However, in many aspects, the development of enabling technologies (for design, operation and decision-making) to achieve this transformation in the construction industry is not as trivial as repackaging existing technologies and tools that have been developed for the manufacturing industry. In this paper, we draw attention to some of the significant research opportunities and challenges that exist in these areas of collaborative design and computer-integrated construction, and outline some related researches at the University of Wisconsin-Madison.     

KINETIC STUDY OF SODIUM SULPHIDE-CARBON DIOXIDE-WATER SYSTEM IN A LAMINAR JET

The kinetics of absorption of carbon dioxide in sodium sulphide solution at 292-305 K was studied in a laminar jet apparatus. The absorption of carbon dioxide in liquid is shown to be a diffusion controlled process accompanied by a fast pseudo-first order reaction. The reaction rate constant, k₂, determined for 0.05-0.2 M sodium sulphide solutions depends upon temperature and ionic strength, and the activation energy of the reaction was 52.75 MJ/kmol.