Performance and Buffering Requirements of Internet Protocols over ATM ABR and UBR Services

The Asynchronous Transfer Mode (ATM) networks are quickly being adopted as backbones over various parts of the Internet. This paper analyzes the performance of TCP/IP protocols over ATM network's Available Bit Rate (ABR) and Unspecified Bit Rate (UBR) services. It is shown that ABR pushes congestion to the edges of the ATM network while UBR leaves it inside the ATM portion.Comment: IEEE Communications Magazine, Vol 36, no 6, pp152-15

Performance of Bursty World Wide Web (WWW) Sources over ABR

We model World Wide Web (WWW) servers and clients running over an ATM network using the ABR (available bit rate) service. The WWW servers are modeled using a variant of the SPECweb96 benchmark, while the WWW clients are based on a model by Mah. The traffic generated by this application is typically bursty, i.e., it has active and idle periods in transmission. A timeout occurs after given amount of idle period. During idle period the underlying TCP congestion windows remain open until a timeout expires. These open windows may be used to send data in a burst when the application becomes active again. This raises the possibility of large switch queues if the source rates are not controlled by ABR. We study this problem and show that ABR scales well with a large number of bursty TCP sources in the system.Comment: Submitted to WebNet `97, Toronto, November 9

Deep Learning Based NLOS Identification with Commodity WLAN Devices

Identifying line-of-sight (LOS) and non-LOS (NLOS) channel conditions can improve the performance of many wireless applications, such as signal strength-based localization algorithms. For this purpose, channel state information (CSI) obtained by commodity IEEE 802.11n devices can be used, because it contains information about channel impulse response (CIR). However, because of the limited sampling rate of the devices, a high-resolution CIR is not available, and it is difficult to detect the existence of an LOS path from a single CSI measurement, but it can be inferred from the variation pattern of CSI over time. To this end, we propose a recurrent neural network (RNN) model, which takes a series of CSI to identify the corresponding channel condition. We collect numerous measurement data under an indoor office environment, train the proposed RNN model, and compare the performance with those of existing schemes that use handcrafted features. The proposed method efficiently learns a non-linear relationship between input and output, and thus, yields high accuracy even for data obtained in a very short period.Comment: 9 pages, 9 figures, Accepted for publication in IEEE Transactions on Vehicular Technolog

Optimal power flow based congestion management using enhanced genetic algorithms

Congestion management (CM) in the deregulated power systems is germane and of central importance to the power industry. In this paper, an optimal power flow (OPF) based CM approach is proposed whose objective is to minimize the absolute MW of rescheduling. The proposed optimization problem is solved with the objectives of total generation cost minimization and the total congestion cost minimization. In the centralized market clearing model, the sellers (i.e., the competitive generators) submit their incremental and decremental bid prices in a real-time balancing market. These can then be incorporated in the OPF problem to yield the incremental/ decremental change in the generator outputs. In the bilateral market model, every transaction contract will include a compensation price that the buyer-seller pair is willing to accept for its transaction to be curtailed. The modeling of bilateral transactions are equivalent to the modifying the power injections at seller and buyer buses. The proposed CM approach is solved by using the evolutionary based Enhanced Genetic Algorithms (EGA). IEEE 30 bus system is considered to show the effectiveness of proposed CM approach

Energy audit: types, scope, methodology and report structure

The objective of this paper is to study various methods adopted during the energy audit. Many countries are focusing on energy, not only enhancing the tenable power generation sources but also on utilizing the power more proficiently for economic utilization. The energy audit is an important parameter for all the developing and developed countries and they focus on energy efficiency, energy quality, and energy intensity. In the industrial, residential, and commercial sectors the top operating expense is found to be are material, machine, manpower, and energy. Identification of the energy-consuming sector is the prior attention to look for the energy-saving potential and quality improvement. Implementation of an energy audit can enhance the efficiency, quality of power, reduce the tariff of bills, and reduces the wastage of energy. The need for energy audits, different types of energy audits, various types of software used, and the energy audit report structure were presented in this paper

Inverse Analysis of UHPFRC Beams with a Notch to Evaluate Tensile Behavior

Recently, ultra high performance fiber reinforced concrete (UHPFRC) has been developed to attain considerably increased compressive cracking strength and ductile tensile behavior with high tensile strength through adding straight steel fibers in concrete mixture. Although benefits with UHPFRC were investigated through experimental program, it is difficult to predict structural behavior of UHPFRC members since theoretical approaches are limited. In this paper, inverse analysis procedure has been proposed for a three-point bending test with notched UHPFRC beams so that tensile behavior of UHPFRC could be rationally evaluated. On the inverse analysis procedure, failure mode of the UHPFRC beam was simplified and the simplified diverse embedment model (SDEM) was employed. To verify the proposed inverse analysis procedure, UHPFRC beams with a notch were analyzed with the tensile behavior of UHPFRC evaluated through the inverse analysis procedure. The analytical predictions showed good agreement with the load-crack mouth opening displacement (CMOD) responses measured through the three-point bending test. Consequently, it can be concluded that UHPFRC tensile behavior can be rationally evaluated through the proposed inverse analysis procedure. The proposed inverse analysis procedure can be useful in relevant research areas such as development of advanced design approaches or computational methods for UHPFRC members