Adapting a delay-based protocol to heterogeneous environments

We investigate the issues in making a delay-based protocol adaptive to heterogeneous environments. We assess and address the problems a delay-based protocol faces when competing with a loss-based protocol such as TCP. We investigate if noise and variability in delay measurements in environments such as cable and ADSL access networks impact the delay-based protocol behavior significantly. We investigate these issues in the context of incremental deployment of a new delay-based protocol, PERT. We propose design modifications to PERT to compete with the TCP flavor SACK. We show through simulations and real network experiments that, with the proposed changes, PERT experiences lower drop rates than SACK and leads to lower overall drop rates with different mixes of PERT and SACK protocols. Delay-based protocols, being less aggressive, have problems in fully utilizing a highspeed link while operating alone. We show that a single PERT flow can fully utilize a high-speed, high-delay link. We performed several experiments with diverse parameters and simulated numerous scenarios using ns-2. The results from simulations indicate that PERT can adapt to heterogeneous networks and can operate well in an environment of heterogeneous protocols and other miscellaneous scenarios like wireless networks (in the presence of channel errors). We also show that proposed changes retain the desirable properties of PERT such as low loss rates and fairness when operating alone. To see how the protocol performs with the real-world traffic, the protocol has also been implemented in the Linux kernel and tested through experiments on live networks, by measuring the throughput and losses between nodes in our lab at TAMU and different machines at diverse location across the globe on the planet-lab. The results from simulations indicate that PERT can compete with TCP in diverse environments and provides benefits as it is incrementally deployed. Results from real-network experiments strengthen this claim as PERT shows similar behavior with the real-world traffic

ReSchedule Sistem Perpipaan Water Treatment Plant Pada PLTGU dengan Metode FLASH (Fuzzy Logic Applications For Scheduling) – Metode Dual Shift.

Abstract - The construction of the piping system installation construction of Water Treatment Plant which was scheduled with a duration of 300 days in 12 months encountered a delay. A delay of procurement activites for 66 days due to the incorrect material supplied resulted in construction activities being hampered. Therefore, a penalty of 0.001 percent of the contract value per day was paid by the company. A rescheduling analysis was required to finish the project especially in the construction activites. In this study, rescheduling was carried out using a comparison of the PERT - Dual Shift and FLASH - Dual Shift methods based on the optimum time and minimum cost. From the results of the analysis, it can be explained that rescheduling of 390 days duration using PERT method resulted in smaller cost compared with PERT - Dual Shift method with a difference of 170 days duration. While the FLASH method with a duration of 366 days resulted in a smaller cost compared to FLASH – Dual shift Method with a duration of 183 days. Based on the analysis, it was also found that the FLAS showed that the minimum cost and the optimum time compared with Pert Method. So, FLASH method is more recommended for rescheduling of the project in this study considering, the minimum cost and optimum time

Adapting a delay-based protocol to heterogeneous environments

We investigate the issues in making a delay-based protocol adaptive to heterogeneous environments. We assess and address the problems a delay-based protocol faces when competing with a loss-based protocol such as TCP. We investigate if noise and variability in delay measurements in environments such as cable and ADSL access networks impact the delay-based protocol behavior significantly. We investigate these issues in the context of incremental deployment of a new delay-based protocol, PERT. We propose design modifications to PERT to compete with the TCP flavor SACK. We show through simulations and real network experiments that, with the proposed changes, PERT experiences lower drop rates than SACK and leads to lower overall drop rates with different mixes of PERT and SACK protocols. Delay-based protocols, being less aggressive, have problems in fully utilizing a highspeed link while operating alone. We show that a single PERT flow can fully utilize a high-speed, high-delay link. We performed several experiments with diverse parameters and simulated numerous scenarios using ns-2. The results from simulations indicate that PERT can adapt to heterogeneous networks and can operate well in an environment of heterogeneous protocols and other miscellaneous scenarios like wireless networks (in the presence of channel errors). We also show that proposed changes retain the desirable properties of PERT such as low loss rates and fairness when operating alone. To see how the protocol performs with the real-world traffic, the protocol has also been implemented in the Linux kernel and tested through experiments on live networks, by measuring the throughput and losses between nodes in our lab at TAMU and different machines at diverse location across the globe on the planet-lab. The results from simulations indicate that PERT can compete with TCP in diverse environments and provides benefits as it is incrementally deployed. Results from real-network experiments strengthen this claim as PERT shows similar behavior with the real-world traffic

PEKERJAAN EARTHWORK DENGAN PENERAPAN METODE M-PERT DI AREA KAWASAN INDUSTRI

Earthwork Work with the Application of the PERT-Method in the Industrial Estate area. At the present time the need for industrial area in Jakarta and its surrounding areas is much higher than its availability. The average delay in earthwork  is 6.1% white the weight of earthwork work in a construction project reacted 13.48%.In order to overcome the delay in implementation time, researchers used the M-PERT method can increase the accuracy of implementation time by 99%, The processing The results of the statistical analysis obtained the influential factors in earthwork work on industrial areas based on the M-PERT method whice are: exavator selection, similarities in the network, combining activities, understanding PERT activities, manual calculation, recalculating PERT, increasing crashing time, identification of cut & fill and effects duration of activity. Based on the validation results on the ripening work of the G1 plots in the industrial zone of Krakatau II Cilegon Banten, the application of  M-PERT method, the result is 72 , 55 days, whice produced  the error rate of 1.99%

Resource Schedule of Concrete Fish Pond Construction Using Network Analysis

In the construction of building, preparation of bid, maintenance and planning of oil refinery and preparation for agricultural activities, there is a need to know the completion days of the project without delay and the earliest time and the latest time for which each activity will take. It was based on this that we decide to analyze the construction of concrete fish pond using Network Analysis through the use of Critical Path Method (CPM) and Program Evaluation Review Technique (PERT). Sixty-four days was arrived at for the completion of the construction using CPM while sixty-eight days with 99% probability was arrived at using PERT method. In deciding which of the method is best suitable for the construction of the fish pond, PERT serve as the best method due to the fact that it considers the Pessimistic Time (longest time possible and can be seen as usual delay) and Optimistic Time (shortest time possible if things go perfectly) as well as the probability [which is 99%] of completing the task within a specific time. The result established some useful facts for researchers in this area as well as managers of industry in carrying out their study from the feasibility stage to the other stages so as to have a good practical target towards the completion of the project as planned. Keyword: Network Analysis, Critical Path Method, Program Evaluation Review Technique, Pessimistic Time, Optimistic Time and Probability DOI: 10.7176/JMCR/57-04 Publication date:June 30th 201

Analisis Penjadwalan Proyek Remote Terminal Unit dengan Penerapan Metode CPM dan PERT di PT. XYZ

ABSTRACT Analysis of the project implementation needs to be done so that deficiency andweaknesses can be identified, as well as problems encountered so that they can beused as reference material for subsequent projects. Project delays are often caused by lack of planned project activities and lack of control over the course of the project so that project implementation activities become less effective and efficient. The Critical Path Method (CPM) and PERT (Program Evaluation and Review Tecnique) are carried out to get an idea of what if the project is controlled by the two tools. Analysis of research results from the Remote Terminal Unit (RTU) project using the CPM method obtained a completion time of 104 days, while completion by the PERT method obtained time of 106.7 days with a probability of 99.99% completion and by processing the Fishbone Diagram there was a cause for the delay factor The biggest is the existence of material delays and the lack of supervision from the company. Keywords : Scheduling, CPM and PERT Methods, Fishbone Diagrams.

OPTIMALISASI WAKTU DAN BIAYA PROYEK DENGAN METODE CPM DAN PERT DI PROYEK ABC CONDOTEL

Planning until controlling process during construction work are important activity of a project. Success or failing of the project caused by not maximal planning and insufficiently effective controlling, so that the project activity is inefficient. As the consequences of these impacts suffered project delay, decreasing of quality, and increasing performing cost. Project management working time drew the line by given schedule, so the manager of project shall get to anticipate condition changing. CPM and PERT methods can be used to manage the time of project completion more efficiently and effectively. To be able to reduce the impact of delays and swelling of project costs, a crashing process can be proposed with additional working hours. Duration acceleration is carried out on the work that is on the critical path because the work on the critical path does not have a delay time. With the addition of working hours besides being able to shorten the completion time, it also results in additional operational costs. Keywords : Project management, CPM and PERT method

Evaluation of Probabilistic Early Response TCP (PERT) for Video Delivery and Extension with ACK Coalescing

This thesis demonstrates the performance of Probabilistic Early Response TCP (PERT), a new TCP congestion control, for video streaming. As a delay based protocol, it measures the delay at the end host and adjusts the congestion window accordingly. Our experiments show that PERT improves video delivery performance by decreasing the fraction of packets delivered late. Furthermore, our Linux live streaming test indicates that PERT is able to reduce the playback glitches, when high resolution video is delivered over a link with non-zero packet loss. In order to operate PERT at higher thoughputs, we design PERT to work with Acknowledgement (ACK) coalescing at the receiver. ACK coalescing makes data transfers burstier and makes it hard to estimate delays accurately. We apply TCP pacing to fix this issue, and validate its effectiveness in the aspects of throughput, packet loss and fairness. Our experiment results also show that PERT with Delayed ACK and Pacing is more friendly, and therefore more suitable when multiple traffic flows are competing for limited bottleneck bandwidth or sharing the same router buffer

Computational Methods for Probabilistic Inference of Sector Congestion in Air Traffic Management

This article addresses the issue of computing the expected cost functions from a probabilistic model of the air traffic flow and capacity management. The Clenshaw-Curtis quadrature is compared to Monte-Carlo algorithms defined specifically for this problem. By tailoring the algorithms to this model, we reduce the computational burden in order to simulate real instances. The study shows that the Monte-Carlo algorithm is more sensible to the amount of uncertainty in the system, but has the advantage to return a result with the associated accuracy on demand. The performances for both approaches are comparable for the computation of the expected cost of delay and the expected cost of congestion. Finally, this study shows some evidences that the simulation of the proposed probabilistic model is tractable for realistic instances.Comment: Interdisciplinary Science for Innovative Air Traffic Management (2013

A study of project planning on Libyan construction projects

Construction projects are regularly faced by scheduling problems causing the projects to finish beyond their predetermined due date; this is a global phenomenon. The main purpose of this study is to consider the problems associated with project planning generally, with specific reference to construction projects in Libya. This study is unique in two respects. First, despite the recent high volume of infrastructure work in the country, there have been few investigations into construction delays in Libya. Secondly, earlier studies have considered the causes or the effects of project delays, whereas the present aim is to evaluate the potential of applying a planning and scheduling technique that is entirely novel in the Libyan context. The paper reports the results of Phase I of this research