A New Technique for Estimating the Distribution of a Stochastic Project Makespan

2012 ◽  
pp. 33-47
Author(s):  
Yuval Cohen ◽  
Ofer Zwikael
Keyword(s):  
Project Scheduling ◽  
Time Distribution ◽  
Start Time ◽  
Time Duration ◽  
Project Duration ◽  
Critical Success ◽  
Activity Networks ◽  
Computation Scheme ◽  
Simulation Results ◽  
A New Technique

A critical success dimension in projects is the ability to complete a project within an estimated duration. In that regard, effective project scheduling techniques in an uncertain environment is of interest in many organizations. In this paper, the authors use an analytic approach to analyze the behavior of time duration distributions of projects in stochastic activity networks, and propose a simple computation scheme for approximating their distribution. The findings offer an understanding of the large gap between PERT and simulation results, and the deviation of projects from their intended schedules. In addition to providing theoretical framework, the proposed approach also recommends a simple practical pragmatic technique that computes the time distribution of project duration. This is a simple and handy tool for the project manager that may replace simulation. As a byproduct, the earliest start time distribution for each activity is also estimated.

A New Technique for Estimating the Distribution of a Stochastic Project Makespan

2010 ◽  
Vol 1 (3) ◽  
pp. 14-27 ◽  
Author(s):  
Yuval Cohen ◽  
Ofer Zwikael
Keyword(s):  
Time Distribution ◽  
Project Manager ◽  
Start Time ◽  
Time Duration ◽  
Project Duration ◽  
Stochastic Activity Networks ◽  
Critical Success ◽  
Activity Networks ◽  
Computation Scheme ◽  
A New Technique

A critical success dimension in projects is the ability to complete a project within an estimated duration. In that regard, effective project scheduling techniques in an uncertain environment is of interest in many organizations. In this paper, the authors use an analytic approach to analyze the behavior of time duration distributions of projects in stochastic activity networks, and propose a simple computation scheme for approximating their distribution. The findings offer an understanding of the large gap between PERT and simulation results, and the deviation of projects from their intended schedules. In addition to providing theoretical framework, the proposed approach also recommends a simple practical pragmatic technique that computes the time distribution of project duration. This is a simple and handy tool for the project manager that may replace simulation. As a byproduct, the earliest start time distribution for each activity is also estimated.

scholarly journals Comparison of Heuristic Priority Rules in the Solution of the Resource-Constrained Project Scheduling Problem

2021 ◽  
Vol 13 (17) ◽  
pp. 9956
Author(s):  
Osman Hürol Türkakın ◽  
David Arditi ◽  
Ekrem Manisalı
Keyword(s):  
Resource Allocation ◽  
Project Scheduling ◽  
Resource Constraints ◽  
Priority Rules ◽  
Resource Constrained ◽  
Start Time ◽  
Project Duration ◽  
Resource Constrained Project Scheduling ◽  
Finish Time ◽  
Positional Weight

Resource-constrained project scheduling (RCPS) aims to minimize project duration under limited resource availabilities. The heuristic methods that are often used to solve the RCPS problem make use of different priority rules. The comparative merits of different priority rules have not been discussed in the literature in sufficient detail. This study is a response to this research gap. It compares 17 heuristic priority rules and seeks the best performing heuristic priority rule. This is the first study ever that compares heuristic priority rules by considering combinations of variations in (1) resource allocation procedures, (2) number of activities, (3) number of resource constraints, and (4) resource supply levels. The objective is to understand the relative merits of heuristic rules used in solving the RCPS problem. The findings indicate that the “minimum late finish time” rule generates the shortest predicted project duration when used in parallel resource allocation, whereas the “minimum late start time”, “minimum late finish time”, and the “highest rank of positional weight 2” rules perform best in serial resource allocation. It was also found that parallel resource allocation is slightly superior to serial resource allocation in most instances.

An Offset Reduction Technique for Latch Type Sense Amplifier in High Performance and High Density SRAM

2012 ◽  
Vol 542-543 ◽  
pp. 769-774
Author(s):  
Qun Ling Yu ◽  
Na Bai ◽  
Yan Zhou ◽  
Rui Xing Li ◽  
Jun Ning Chen ◽  
...  
Keyword(s):  
High Performance ◽  
Circuit Simulation ◽  
Cmos Technology ◽  
Optimal Operation ◽  
Reduction Technique ◽  
Total Speed ◽  
Sense Amplifier ◽  
Simulation Results ◽  
A New Technique ◽  
Total Energy Dissipation

A new technique for reducing the offset of latch-type sense amplifier has been proposed and effect of enable signal voltage upon latch-type sense amplifier offset in SRAM has been investigated in this paper. Circuit simulation results on both StrongARM and Double-tail topologies show that the standard deviation of offset can be reduced by 31.23% (StrongARM SA) and 25.2% (Double-tail SA) , respectively, when the voltage of enable signal reaches 0.6V in TSMC 65nm CMOS technology. For a column of bit-cell (1024 bit-cell), the total speed is improved by 14.98% (StrongARAM SA) and 22.26% (Double-tail SA) at the optimal operation point separately, and the total energy dissipation is reduced by 30.45% and 29.47% with this scheme.

ACCURATE ANALYSIS OF GLOBAL INTERCONNECTS IN NANO-FPGAs

NANO ◽  
2009 ◽  
Vol 04 (03) ◽  
pp. 171-176 ◽  
Author(s):  
DAVOOD FATHI ◽  
BEHJAT FOROUZANDEH
Keyword(s):  
Propagation Delay ◽  
Modeling Method ◽  
Accurate Analysis ◽  
Proposed Model ◽  
Simulation Results ◽  
The Difference ◽  
A New Technique ◽  
Global Interconnects ◽  
Technology Nodes ◽  
Model Technique

This paper introduces a new technique for analyzing the behavior of global interconnects in FPGAs, for nanoscale technologies. Using this new enhanced modeling method, new enhanced accurate expressions for calculating the propagation delay of global interconnects in nano-FPGAs have been derived. In order to verify the proposed model, we have performed the delay simulations in 45 nm, 65 nm, 90 nm, and 130 nm technology nodes, with our modeling method and the conventional Pi-model technique. Then, the results obtained from these two methods have been compared with HSPICE simulation results. The obtained results show a better match in the propagation delay computations for global interconnects between our proposed model and HSPICE simulations, with respect to the conventional techniques such as Pi-model. According to the obtained results, the difference between our model and HSPICE simulations in the mentioned technology nodes is (0.29–22.92)%, whereas this difference is (11.13–38.29)% for another model.

scholarly journals Analog Low-Voltage Current-Mode Implementation of Digital Logic Gates

2003 ◽  
Vol 26 (2) ◽  
pp. 111-114 ◽  
Author(s):  
Muhammad Taher Abuelma'atti
Keyword(s):  
Power Series ◽  
Low Voltage ◽  
Logic Gates ◽  
Current Mode ◽  
New Technique ◽  
Basic Logic ◽  
Spice Simulation ◽  
Simulation Results ◽  
A New Technique ◽  
Logic Functions

In this letter a new technique is introduced for implementing the basic logic functions using analog current-mode techniques. By expanding the logic functions in power series expressions, and using summers and multipliers, realization of the basic logic functions is simplified. Since no transistors are working in saturation, the problem of fan-out is alleviated. To illustrate the proposed technique, a circuit for simultaneous realization of the logic functions NOT, OR, NAND and XOR is considered. SPICE simulation results, obtained with 3 V supply, are included

Modeling and Simulation of Tri-Pole HVDC Transmission System

2013 ◽  
Vol 347-350 ◽  
pp. 1303-1307 ◽  
Author(s):  
Si Zhuo Lv ◽  
Jun Wen ◽  
Jia Liang Wen ◽  
We Yyang Yin ◽  
Jing Wu
Keyword(s):  
Transmission Line ◽  
Modeling And Simulation ◽  
Basic Principle ◽  
Power Demand ◽  
Land Resources ◽  
Hvdc Transmission ◽  
Protection Strategies ◽  
Simulation Results ◽  
A New Technique ◽  
Ac Transmission

With the increase of the power demand and reduction of land resources, it is imperative to increase AC transmission line capacity. Tri-pole HVDC is proposed as a new technique to solve this problem. This paper presents the basic principle of tri-pole HVDC, including its schematic and current modulation strategy. Based on the platform of PSCAD/EMTDC a tri-pole simulation model is built to carry out the simulation on deblock startup and block shun down. Besides, a cooperation mode of the controller with the protection under emergency outage of single converter station or under fault occurred in DC transmission line is put forward, and simulation results show that the proposed control and protection strategies are effective.

The Study on Starting Control of ER Clutch for Vehicle

2012 ◽  
Vol 490-495 ◽  
pp. 1759-1762 ◽  
Author(s):  
Jian Hua Wang ◽  
Hao Xu ◽  
Fei Xie
Keyword(s):  
Control Strategy ◽  
Control Voltage ◽  
Start Time ◽  
Evaluation Indexes ◽  
Working Principle ◽  
Simulation Results ◽  
And Control ◽  
Start Process ◽  
Er Fluid ◽  
Starting Control

This paper proposed a new design scheme for automatic clutch of AMT which is based on electrorheological (ER) fluid. Through analyzing the working principle and its transfer characteristics of ER fluid, it discussed the start process of vehicle and control strategy of ER Clutch. By changing the control voltage, ER clutch satisfied the requirements of evaluation indexes such as start time and impact degree. The simulation results showed that the control strategy can realize starting rapidly and steadily which would meet the start requirements of economical automobiles

scholarly journals Results on a Binding Neuron Model and Their Implications for Modified Hourglass Model for Neuronal Network

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Viswanathan Arunachalam ◽  
Raha Akhavan-Tabatabaei ◽  
Cristina Lopez
Keyword(s):  
Time Distribution ◽  
Single Neuron ◽  
Statistical Characteristics ◽  
Recurrent Networks ◽  
Integrate And Fire ◽  
Classical Models ◽  
Simulation Results ◽  
Hourglass Model ◽  
Fixed Period ◽  
Integrate And Fire Neuron

The classical models of single neuron like Hodgkin-Huxley point neuron or leaky integrate and fire neuron assume the influence of postsynaptic potentials to last till the neuron fires. Vidybida (2008) in a refreshing departure has proposed models for binding neurons in which the trace of an input is remembered only for a finite fixed period of time after which it is forgotten. The binding neurons conform to the behaviour of real neurons and are applicable in constructing fast recurrent networks for computer modeling. This paper develops explicitly several useful results for a binding neuron like the firing time distribution and other statistical characteristics. We also discuss the applicability of the developed results in constructing a modified hourglass network model in which there are interconnected neurons with excitatory as well as inhibitory inputs. Limited simulation results of the hourglass network are presented.

scholarly journals Analysis of an Anomaly: The Increase in Time Float following Consumption

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Jianxun Qi ◽  
Zhixiong Su
Keyword(s):  
Completion Time ◽  
Start Time ◽  
Project Completion ◽  
Activity Networks ◽  
Different Types ◽  
Project Plan ◽  
Time Float

One fundamental axiom for project plan and schedule relates to the notion that time float will be reduced following its consumption. However, an anomalous scenario can emerge in which an activity’s time float increases following its consumption. By exploring the associations between time float and paths in activity networks, we (a) reveal the conditions under which the anomaly occurs and (b) summarize laws related to total float. An activity’s total float increases in parallel with its duration prolongation within a given boundary but remains constant or decreases in parallel with a prolongation outside the boundary. Furthermore, whereas a prolongation of an activity’s duration in excess of classic total float does not delay project completion time, a lag of its start time to a degree slightly greater than the total float does. This analysis reveals different types of total float that correspond to different ways of usage. From this, we offer definitions for translation total float and prolongation total float that deviate from traditional conventions regarding the uniqueness of total float.

scholarly journals Cost Optimal Project Scheduling

Organizacija ◽  
2008 ◽  
Vol 41 (4) ◽  
pp. 153-158
Author(s):  
Uroš Klanšek ◽  
Mirko Pšunder
Keyword(s):  
Nonlinear Programming ◽  
Objective Function ◽  
Project Scheduling ◽  
Programming Approach ◽  
Project Duration ◽  
Numerical Example ◽  
Activity Duration ◽  
The Cost ◽  
Total Project Cost ◽  
Total Project

Cost Optimal Project SchedulingThis paper presents the cost optimal project scheduling. The optimization was performed by the nonlinear programming approach, NLP. The nonlinear total project cost objective function is subjected to the rigorous system of the activity precedence relationship constraints, the activity duration constraints and the project duration constraints. The set of activity precedence relationship constraints was defined to comprise Finish-to-Start, Start-to-Start, Start-to-Finish and Finish-to-Finish precedence relationships between activities. The activity duration constraints determine relationships between minimum, maximum and possible duration of the project activities. The project duration constraints define the maximum feasible project duration. A numerical example is presented at the end of the paper in order to present the applicability of the proposed approach.

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