Generating effective project scheduling heuristics by abstraction and reconstitution

A project scheduling problem consists of a finite set of jobs, each with fixed integer duration, requiring one or more resources such as personnel or equipment, and each subject to a set of precedence relations, which specify allowable job orderings, and a set of mutual exclusion relations, which specify jobs that cannot overlap. No job can be interrupted once started. The objective is to minimize project duration. This objective arises in nearly every large construction project--from software to hardware to buildings. Because such project scheduling problems are NP-hard, they are typically solved by branch-and-bound algorithms. In these algorithms, lower-bound duration estimates (admissible heuristics) are used to improve efficiency. One way to obtain an admissible heuristic is to remove (abstract) all resources and mutual exclusion constraints and then obtain the minimal project duration for the abstracted problem; this minimal duration is the admissible heuristic. Although such abstracted problems can be solved efficiently, they yield inaccurate admissible heuristics precisely because those constraints that are central to solving the original problem are abstracted. This paper describes a method to reconstitute the abstracted constraints back into the solution to the abstracted problem while maintaining efficiency, thereby generating better admissible heuristics. Our results suggest that reconstitution can make good admissible heuristics even better

The Relationship between Working Capital Management Efficiency and EBIT

This paper is aimed at analyzing the relationship between Working Capital Management Efficiency (WCME) and Earnings before Interest&Taxes (EBIT) of the Paper Industry in India during 1997–1998 to 2005–2006. Tomeasure the WCME three index values viz., Performance Index (PI), Utilization Index (UI), and Efficiency Index (EI) are computed, and are associated with explanatory variables, viz., Cash Conversion Cycle (CCC), Accounts Payable Days (APDAYS), Accounts Receivables Days (ARDAYS), Inventory Days (INVDAYS). Further, Fixed Financial Assets Ratio (FIXDFARA), Financial Debt Ratio (FINDBTRA) and Size (Natural log of Sales) are considered as control variables in the analysis, and are associated with the EBIT. The study reveals that the Paper Industry has managed the WC satisfactorily. The APDAYS has a significant (–)ve relationship with EBIT, which indicates that by deploying payment to suppliers they improve the EBIT. The Paper Industry in India performs remarkably well during the period, however, less profitable firms wait longer to pay their bills, and pursue a decrease in CCC.Working Capital Management Efficiency, Earnings before Interest and Taxes, Current Assets, Current Liabilities, Performance Index, Utilization Index, Efficiency Index

Design and Analysis of SD_DWCA - A Mobility based clustering of Homogeneous MANETs

This paper deals with the design and analysis of the distributed weighted clustering algorithm SD_DWCA proposed for homogeneous mobile ad hoc networks. It is a connectivity, mobility and energy based clustering algorithm which is suitable for scalable ad hoc networks. The algorithm uses a new graph parameter called strong degree defined based on the quality of neighbours of a node. The parameters are so chosen to ensure high connectivity, cluster stability and energy efficient communication among nodes of high dynamic nature. This paper also includes the experimental results of the algorithm implemented using the network simulator NS2. The experimental results show that the algorithm is suitable for high speed networks and generate stable clusters with less maintenance overhead

Cell Utilization Efficiency of Internet Protocol Traffic over Asynchronous Transfer Mode Networks

In the near future, large computer networks will be connection oriented, with at least the data link connectivity being provided by the Asynchronous Transfer Mode. (ATM) networks. However, these networks may have to communicate with the existing network which predominantly use Internet Protocol (IP). Running Internet Protocol over Asynchronous Transfer Mode Network has been a contentious issue due to the inefficient segmentation of Internet Protocol packets into Asynchronous Transfer Mode (ATM) cells. In this thesis, the current protocols and standards pertaining to Internet Protocol over Asynchronous Transfer Mode are discussed and overheads involved in placing Internet Protocol packets into Asynchronous Transfer Mode cells, taking Logical Link Control/Sub Network Attachment Point Encapsulation into consideration, are analysed to find out the cell utilization of Asynchronous Transfer Mode cell in carrying the Internet Protocol packets. The Wide Area Network (WAN) oriented traffic for our analysis is collected from the Internet Traffic Archive. Analysis of the trace results show that the Asynchronous Transfer Mode cell utilisation is better in carrying the user information if the Internet Protocol packet are sizes larger. It is observed that ranges of Internet Protocol packets require similar number of Asynchronous Transfer Mode cells. At small values of Internet Protocol packets, the efficiency of Asynchronous Transfer Mode cell in carrying the user information is significantly low due to the Logical Link Control Encapsulation, padding and the trailer overheads. The Asynchronous Transfer Mode Cell utilization is better in Virtual Circuit (VC) based multiplexing, saving 8 bytes of encapsulation for each packet, thus improving the Asynchronous Transfer Mode (ATM) cell utilization marginally. It is seen that 80% of the Internet Protocol packet length varies from 54 to 200 bytes for which cell utilisation varies from 50%-to 82%. However, the average cell utilisation is 84% in the 20,000 packets observed since 20% of the Internet Protocol packet length is greater than 1000 bytes

A simple and efficient dye-based technique for rapid screening of fungi for L-asparaginase production

Three hundred and sixty four (364) isolates of tropical soil fungi were screened for L-asparaginase production by rapid plate method using modified Czapek-Dox agar containing L-asparagine, and either bromo cresol purple or phenol red dye as an indicator. Results of the study revealed that total one hundred and thirty five (135) isolates showed positive reaction for L-asparaginase production as indicated by the color change in and around the colonies between 48-72 hours of incubation at 280 C. A comparative study of the two indicator dyes with varying concentrations showed bromo cresol purple is a better and efficient indicator for L-asparaginase screening than phenol red. Quantitative estimation of L-asparaginase in the selected fungi showed Aspergillus sp. and Fusarium sp. were good candidates for L-asparaginase production