High-utility and diverse itemset mining

High-utility Itemset Mining (HUIM) finds patterns from a transaction database with their utility no less than a user-defined threshold. The utility of an itemset is defined as the sum of the utilities of its items. The utility notion enables a data analyst to associate a profit score with each item and thereof to a pattern. We extend the notion of high-utility with diversity to define a new pattern type called High-utility and Diverse pattern (HUD). The notion of diversity of a pattern captures the extent of the different categories covered by the selected items in the pattern. An application of diverse-pattern lies in the recommendation task where a system can recommend to a customer a set of items from a new class based on her previously bought items. Our notion of diversity is easy to compute and also captures the basic essence of a previously proposed diversity notion. The existing algorithm to compute frequent-diverse patterns is 2-phase, i.e., in the first phase, frequent patterns are computed, out of which diverse patterns are filtered out in the second phase. We, in this paper, give an integrated algorithm that efficiently computes high-utility and diverse patterns in a single phase. Our experimental study shows that our proposed algorithm is very efficient as compared to a 2-phase algorithm that extracts high-utility itemsets in the first phase and filters out the diverse itemsets in the second phase.

     

Synthesis and characterization of hydroxamic acid resin of poly(4-vinyl-2′-carboxybenzophenone)

The synthesis and characterization of poly(hydroxamic acid) ion-exchange resin from a poly(carboxylic acid) resin is described and its exchange properties for Cu(II), Ni(II), and Fe(III) are studied. The metal polychelates are investigated by magnetic measurements, diffuse reflectance spectroscopy, and infrared spectroscopy. © 1994 John Wiley & Sons, Inc.     

EXPERIMENTAL EVALUATION OF SELECTIVITY IN SLOW AROMATIC CHLORINATIONS

A dispersion plug flow reactor model (DPFR) has been derived and experimentally verified to predict product distribution and selectivity for commercial aromatic halogenation reactions. From the model recommendations for process modifications to reduce the amounts of undesirable byproducts arising from similar reactions can be obtained. The selectivity of the monochlorinated product is shown to depend on kinetic and hydrodynamic parameters, mixing in the reactor and chlorine solubility. The pertinent variables are arranged in five dimensionless groups which include the kinetic and hydrodynamic Damkohler Numbers, the Peclet Number, ratio of the rate constants and the ratio of chlorine solubility to the inlet aromatic concentration.

A micro pilot plant which duplicates industrial conditions for benzene and toluene chlorination was constructed to test the DPFR model. Chlorination studies were performed under a range of conditions. Hydrodynamic parameters required for the model were obtained from published correlations. The model prediction of selectivity agreed within 8% for all the experimental results, and actually better than 5% for most runs.

A graphical technique which provides recommendations for reducing the dichlorinated products is presented along with examples for both the design of a reactor, and troubleshooting of an existing reactor system.     

Solution of PDEs-electrically coupled systems with electrical analogy

This paper presents an approach to solve coupled systems where electrical/mechanical devices, whose behaviour is governed by a PDE or a system of PDEs, are connected together through an electrical circuit. In an earlier paper [1], it had been shown that PDEs can be modeled by an electrical equivalent circuit generated from the complete set of equations arising from the Finite Element Method (FEM). In this paper, the approach is extended to solve a system of PDEs. The approach allows the simulation of coupled systems with circuit simulation tools alone since the resultant system becomes an electrical circuit after an application of electrical analogy. The coupled system is solved by directly replacing PDE devices with the equivalent circuits. Further, a special circuit simulation technique, viz. multiport decomposition is used in order to solve a large coupled system. A sequential as well as a parallel simulator is built for coupled problems based on the proposed approach. A circuit with 100 linear PDE devices (the equivalent circuit contains 8 million nodes) has been simulated using the parallel simulator in less than 1 h. We have achieved a speedup of 5 over the sequential simulator using 8 processors on distributed memory architecture. The characteristic of p–n junction diode (drift–diffusion equation) is analyzed by our circuit simulator to show that the proposed approach can be used to build a circuit-cum-device simulator.     

FPGA Based High Performance Double-Precision Matrix Multiplication

We present two designs (I and II) for IEEE 754 double precision floating point matrix multiplication, optimized for implementation on high-end FPGAs. It forms the kernel in many important tile-based BLAS algorithms, making an excellent candidate for acceleration. The designs, both based on the rank-1 update scheme, can handle arbitrary matrix sizes, and are able to sustain their peak performance except during an initial latency period. Through these designs, the trade-offs involved in terms of local-memory and bandwidth for an FPGA implementation are demonstrated and an analysis is presented for the optimal choice of design parameters. The designs, implemented on a Virtex-5 SX240T FPGA, scale gracefully from 1 to 40 processing elements(PEs) with a less than 1% degradation in the design frequency of 373 MHz. With 40 PEs and a design speed of 373 MHz, a sustained performance of 29.8 GFLOPS is possible with a bandwidth requirement of 750 MB/s for design-II and 5.9 GB/s for design-I. This compares favourably with both related art and general purpose CPU implementations.     

Development of a computer algorithm based on a conjugate gradient approach for optimization of fed-batch fermentations

The problem of optimization of fed-batch fermentations using the substrate feed rate as the control variable is singular in nature. Previous approaches, including the boundary condition iteration method and transformation to a nonsingular problem using a different control variable, do not work well for solving optimization of systems governed by more than four differential equations. The applicability of a first-order conjugate gradient algorithm for optimizing fed-batch fermentations was tested for systems of varing complexity. This approach does not need any variable transformation ora priori knowledge of the control arc sequence. Constraints on the feed rate are handled in a simple and direct manner. The algorithm worked very well for three, four, and five-dimensional singular systems. The correctness of the optimal profile was judged by observing the variation in the sign of the gradient of the Hamiltonian. The gradient was found to be zero during the singular period and had the appropriate sign on the boundary arcs. The optimization method based on conjugated gradient approach can be complementary to the boundary condition iteration method for determination of the exact optimum profile.     

A structure-function-control paradigm for knowledge-based modeling and design of manufacturing workcells

This paper discusses the integration of structural, functional and control knowledge in manufacturing workcell modeling, simulation and design. After an overview of applications of semantic and object-oriented data models in the manufacturing domain, issues relating to the control synthesis for manufacturing workcells are presented. In particular, a data model encompassing functional and control features, along with application domain structural knowledge, is developed. This model assists in explicitly representing the control aspects of engineering design within an object-oriented database and supports a task-level, functionality-driven, manufacturing workcell design. Since manufacturing workcells consist of a number of elements interacting in a complex manner, workcell control design is one of the most difficult steps in the workcell design procedure. Message passage, commonly used in object-oriented databases, provides no explicit modeling of the database behavior. Hence, it can not serve as a tool for the design of system control. On the other hand, Petrinets (PN) have proven successful in describing complex interaction among active agents. This paper will explore the incorporation of Petri nets as a basis for describing application control knowledge within a structure-function-control data model.     

A Management Perspective on Risk of Security Threats to Information Systems

Electronic commerce and the Internet have enabled businesses to reduce costs, attain greater market reach, and develop closer partner and customer relationships. However, using the Internet has led to new risks and concerns. This paper provides a management perspective on the issues confronting CIOs and IT managers: it outlines the current state of the art for security in e-commerce, the important issues confronting managers, security enforcement measure/techniques, and potential threats and attacks. It develops a scheme for probabilistic evaluation of the impact of security threats with some illustrative examples. This methodology may be used to assess the probability of success of attacks on information assets in organizations, and to evaluate the expected damages of these attacks. The paper also outlines some possible remedies, suggested controls and countermeasures. Finally, it proposes the development of cost models which quantify damages of these attacks and the effort of confronting these attacks. The construction of one such cost model for security risk assessment is also outlined. It helps decision makers to select the appropriate choice of countermeasure(s) to minimize damages/losses due to security incidents. Finally, some recommendations for future work are provided to improve the management of security in organizations on the whole.