Dynamic Allocation Scheme Research Articles

Allocation Schemes, Architectures, and Policies for Collaborative Port Scanning Attacks

Most network attackers perform port scanning individually, without synchronization, to find victim hosts. Such port scanning schemes suffer from two problems: first, there are too many duplicate scannings and too much contention among different port scanners; second, a complete port scanning takes a long time to finish. In this paper, we present a fast DHT-based collaborative port scanning scheme that aims to eliminate duplicate scanning, minimize contention, and significantly increase the scanning speed. In collaborative attacks, attackers communicate and collaborate with each other to launch much more powerful attacks. In the DHT-based collaborative port scanning scheme, attackers collaborate to search the network for ports that could be exposed to attacks. We propose different collaborative scanning strategies and analyze their advantages and disadvantages.We discuss the static, dynamic, and hybrid target selection and allocation schemes. We present the algorithm details and discuss the stop and revisit policy for the collaborative port scanners. We conduct experiments to evaluate the performance and overhead of the collaborative port scanning strategies. Experimental results suggest that the proposed collaborative port scanning system significantly increases the efficiency of port scanning and provide insights into many design and implementation issues.

Dynamic Spectrum Management for WCDMA/DVB Heterogeneous Systems

This paper proposes a novel Dynamic Spectrum Management (DSM) scheme for Wideband Code Division Multiple Access (WCDMA) / Digital Video Broadcasting (DVB) heterogeneous systems. Capacity estimation algorithms for both WCDMA and DVB are developed which consider both the user distribution and characteristics of the hybrid services. Based on these algorithms, a new dynamic spectrum allocation scheme is presented which allows for optimum allocation of resources and maximum secondary spectrum usage. Coloring theory is used to significantly reduce DSM complexity while providing near-optimal performance. Numerical results are given which show that the proposed DSM scheme has better performance than Fixed Spectrum Management (FSM).

Performance Evaluation of a Communication Network with Dynamic Bandwidth Allocation and Bulk Arrivals

networks had a separate deployment for each emerging service like Telephone networks, data networks and multimedia networks. In Integrated Services Network the packets are transmitted using efficient statistical multiplexing. In this paper, we develop and analyze a two-node communication network with dynamic bandwidth allocation having bulk arrivals. The performance of the statistical multiplexing is measured by approximating the arrival and the service process with Poisson process and the bulk size is uniform which is chosen such that several of the statistical characteristics of the communication network identically match with the Poisson process. Through mathematical modeling, the performance measures of the communication network like the joint probability generating function of the buffer size distribution, the average content of the buffers, the mean delays in transmission, the throughput of the nodes and utilization are derived explicitly under transient conditions. Through numerical studies, the sensitivity of the input parameters on the performance measures is also carried. It is observed that the dynamic bandwidth allocation strategy and bulk size distribution of the arrivals have significant effect on the performance measures. This network is much useful in satellite communications and Internet service providing, etc,

Nonlinear dynamic allocator for optimal input/output performance trade-off: Application to the JET tokamak shape controller

In this paper, we revisit the dynamic allocation scheme for input redundant plants proposed in Zaccarian (2009). within a set-point regulation setting and propose generalizations that apply to cases where the plant under consideration is not input redundant but the control specifications allow us to modify the set-point regulation within certain bounds. In this case, the input allocator is extended to the nonredundant case by allowing it to improve the input allocation selection at the price of some output regulation error. We also establish here desirable convergence properties of the allocator, which were only addressed for the linear case in Zaccarian (2009). In particular, we design the allocator dynamics as the gradient of a cost function and establish its convergence to the minimum of the cost function under some mild conditions. The allocation scheme is applied to the JET tokamak shape controller by illustrating its capabilities to enforce coil currents selections that tend to move away from the saturation limits within the allowable degrees of freedom.

Dynamic robust power allocation games under channel uncertainty and time delays

In this paper, we study dynamic robust power allocation strategies under the imperfectness of the channel state information at the transmitters. Considering unknown payoff functions at the transmitters, we propose an heterogeneous Delayed COmbined fully DIstributed Payoff and Strategy Reinforcement Learning (Delayed-CODIPAS-RL) in which each transmitter learns its payoff function as well as its associated optimal strategies in the long-term. We show that equilibrium power allocations can be obtained using the multiplicative weighted imitative CODIPAS-RLs and Bush-Mosteller based CODIPAS-RL. We also show almost sure convergence to the set of global optima for specific scenarios.

Dynamic Subcarrier and Power Allocation Based on Nash Bargaining Solution in Symmetric Cooperative OFDMA Networks

In this paper, subcarrier and power allocation are jointly considered in a three-node symmetric cooperation orthogonal frequency-division multiple access uplink system. With the help of Nash bargaining solution, the dynamic subcarrier allocation scheme and the adaptive power allocation scheme are proposed for joint optimization. The joint resource allocation is decomposed and solved by dynamic subcarrier allocation algorithm and adaptive power allocation algorithm. Simulation results show the effectiveness of the proposed cooperative scheme.

Dynamic Lifecycle Strategies for Target DateRetirement Funds

1. Anup K. Basu 1. is a lecturer in the School of Economics and Finance at Queensland University of Technology in Brisbane, Australia. (a.basu{at}qut.edu.au) 2. Alistair Byrne 1. is a principal consultant at Investit Ltd in London, U.K. (alistair.byrne{at}investit.com) 3. Michael E. Drew 1. is a professor of finance in the Department of Accounting, Finance and Economics at Griffith University in Brisbane, Australia. (michael.drew{at}griffith.edu.au) <!-- --> 1. To order reprints of this article, please contact Dewey Palmieri at dpalmieri{at}iijournals.com or 212-224-3675 . Lifecycle funds offered to retirement plan participants gradually reduce exposure to stocks as the funds approach the target date of the participants’ retirement.The authors show that such deterministic switching rules produce inferior wealth outcomes for the investor compared to strategies that dynamically alter the allocation between growth and conservative assets based on cumulative portfolio performance relative to a set target.The dynamic allocation strategies proposed in this article exhibit almost stochastic dominance over strategies that unidirectionally switch assets without consideration of portfolio performance. TOPICS: [Retirement][1], [portfolio construction][2] [1]: https://www.pm-research.com/topic/retirement [2]: https://www.pm-research.com/topic/portfolio-construction

Transient Analysis of a Tandem Communication Network with Dynamic Bandwidth Allocation having Two Stage Direct Bulk Arrivals

ABSTRACT Communication network models play a dominant role in optimal utilization of resources. The need for congestion control and to improve quality of service, it is needed to design new communication networks. With this motivation, a two node communication network with dynamic bandwidth allocation (DBA) having two stage bulk arrivals (BA) is introduced and analyzed. The statistical multiplexing of the communication network is developed by characterizing the arrival of packets with compound Poisson process and the transmission completions with Poisson processes. To avoid burstness in buffers, the dynamic bandwidth allocation is adapted utilizing the idle bandwidth in the transmitter depending on content of the buffer. The network performance is evaluated by deriving the performance measures like mean content of the buffers, mean delays in transmitters, throughput of the nodes, utilization of the nodes etc,. The transient analysis of the model reveals that the time has a significant influence on predicting the performance measures of the communication networks. The sensitivity analysis of the model provides evidence that the dynamic bandwidth allocation strategy along with bulk arrival consideration can provide the performance of the network more close to the reality and avoid burstness in buffers. This communication network is much useful for Satellite and Mobile communication, Computer communication etc. This communication network model also includes several of the earlier communication network models as particular cases for specific values of the model parameters.

Power Control for Uplink Transmission With Mobile Users

In this paper, we introduce an uplink transmission model with mobile users, where each user maximizes his/her utility to achieve the best performance. We propose a power allocation scheme for each mobile user when all channel information is available. Moreover, we illustrate that one user would expect to predict the aggregate interference to maximize the utility when the channel information is incomplete. It is shown that this approach forms a game with incomplete information. We demonstrate the prediction rules that can help the mobile users dynamically adjust predictions and apply the Kalman filter to tackle measurement noises. We also illustrate the theoretical bound for the difference between the utility with prediction and that with complete information. Moreover, applying dynamic programming from control theory, we give a dynamic power allocation scheme based on the predictions. Simulation results indicate that our power allocation scheme with complete information and dynamic power allocation with predictions give better performance compared with the scheme with even power allocation. In addition, results under our dynamic power allocation scheme are close to those under the power allocation with complete information.

A Dynamic Resource Allocation Scheme for Inter-Cell Interference Coordination in Cellular OFDMA Systems

This paper presents a novel dynamic subchannel allocation scheme that can improve the cell capacity by coordinating the intercell interference (ICI) in a cellular orthogonal frequency division multiple access (OFDMA) system. The proposed scheme mitigates the ICI by adopting the virtual cell concept and improves the frequency reuse factor through subchannel reuse among different virtual cells. In particular, each virtual cell is assigned a primary and a secondary subchannel group, and each sector base station (BSs) allocates the subchannel resulting in the least ICI in probability out of the candidate subchannels to the mobile stations, dynamically searching from its primary group and then secondary group. In addition, an optional use of pico-cell overlay at the intersection of the virtual cells is also proposed to enhance the fairness of the proposed scheme with the BS-MS distance. Through computer simulation, it is shown that the proposed scheme has the advantages of improved cell capacity and fairness compared to the conventional schemes.

Dynamics of wetland vegetation under multiple stresses: a case study of changes in sawgrass trait, structure, and productivity under coupled plant‐soil‐ microbe dynamics

AbstractThis paper quantifies wetland vegetation dynamics under drought, waterlogging, shading, and nutrient stresses within the coupled plant‐soil‐microbe system. A plant is characterized by three independent traits, namely leaf nitrogen (N) content, specific leaf area (SLA), and allometric carbon (C) allocation to rhizome storage, while plant growth is modelled through a dynamic plant allocation scheme. The modelling of N focuses on the internal cycle in which the aerobic and anaerobic processes are determined by the dynamics of oxygen controlled by plants, microbial aerobic processes, and hydrologic dynamics. The dynamics of water levels and soil moisture are described by a simple hydrologic model with stochastic rainfall and are decoupled from the plant‐soil‐microbe dynamics. Using the model to investigate the dynamics of sawgrass, the results, which are consistent with field observations in the southern Everglades, indicate that SLA decreases with increasing anaerobic condition. The lower SLA maintains high stomatal opening, while at the same time prevents cavitational collapse when sawgrass lowers its root:shoot ratio to reduce C cost in root anaerobic respiration. Given a naturally low but not too scarce level of phosphorus, net N mineralization is higher in the wetter hydrologic regimes because the increase in anaerobic decomposition and N mineralization compensate for the decline in those of aerobes; and the slower growing, more nitrogen efficient anaerobes compete less with plants for N. The optimal traits are the results of several counteracting trends of trade‐offs in C and N economy differently influenced by trait combinations in different wetland environments. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Revision of FMM–Yukawa: An adaptive fast multipole method for screened Coulomb interactions

FMM–Yukawa is a mathematical software package primarily for rapid evaluation of the screened Coulomb interactions of N particles in three dimensional space. Since its release, we have revised and re-organized the data structure, software architecture, and user interface, for the purpose of enabling more flexible, broader and easier use of the package. The package and its documentation are available at http://www.fastmultipole.org/, along with a few other closely related mathematical software packages.

Review of Dynamic Allocation Strategies: Utility Maximization, Option Replication, Insurance, Drawdown Control, Convex/Concave Management

We review the main approaches to dynamically reallocate capital between a risky portfolio and a risk-free account: expected utility maximization; option-based portfolio insurance (OBPI); and drawdown control, closely related to constant proportion portfolio insurance (CPPI). We present a refresher of the theory under general assumptions. We discuss the connections among the different approaches, as well as their relationship with convex and concave strategies. We provide explicit, practicable solutions with all the computations as well as numerical examples. Fully documented code for all the strategies is also provided.

Dynamic hedge fund portfolio construction

In this paper, we provide further evidence on the use of multivariate conditional volatility models in hedge fund risk measurement and portfolio allocation, using monthly hedge fund index return data for the period 1990 to 2009. Building on Giamouridis and Vrontos (2007), we consider a broad set of multivariate GARCH models as well as the simpler exponentially weighted moving average (EWMA) estimator of RiskMetrics (1996). We find that while multivariate GARCH models provide some improvement in portfolio performance over static models, they are generally dominated by the EWMA model. In particular, in addition to providing better risk-adjusted performance, the EWMA model leads to dynamic allocation strategies that have substantially lower turnover and could therefore be expected to involve lower transaction costs. Moreover, we show that these results are robust across low-volatility and high-volatility sub-periods.

Roadmap for the next generation of dynamic function allocation theories and strategies

Dynamic function allocation theories have matured, but not to the extent that they can be implemented in actual environments. The authors identify a roadmap to help to get to that stage, after a brief review of relevant function allocation theories and the gaps in knowledge in adaptive allocation theories. Past research has focused on short‐term implementations of dynamic function allocation, which last for minutes (but never more than a few hours). Stable and enduring implementations of dynamic function allocation, lasting over days or possibly years, require a better and scientific understanding of the interaction among trigger mechanisms, adaptation strategies, and interruption strategies. The possibility of an unintentional consequence of this adaptive allocation, that the automated agent becomes confined to limited levels of automation, has to be ruled out after experimental evidence. © 2010 Wiley Periodicals, Inc. © 2011 Wiley Periodicals, Inc.

Polarization Beamforming PON Doubling Bidirectional Throughput

A low-complexity polarization multiplexed Passive Optical Network (PON) architecture based on Multiple Input Multiple Output (MIMO) polarization beamforming is experimentally demonstrated, achieving twice the throughput for both downstream and upstream transmissions. In addition, a novel dynamic power allocation scheme further improves the loss budget by up to ~1.8 dB in the downstream direction.

A new predictive dynamic priority scheduling in Ethernet passive optical networks (EPONs)

Efficient uplink scheduling in Ethernet passive optical networks (EPONs) is very important for maximizing the network capacity while maintaining the required quality of service (QoS). Several variants of dynamic bandwidth resource allocation have been proposed in recent research literature. However, the available techniques do not fully exploit the elastic properties of the user traffic. In this paper, we explore optimal predictive resource allocation strategies by exploiting the elasticity of QoS-constrained traffic and using the knowledge of traffic patterns of different service classes. We propose a predictive dynamic uplink bandwidth allocation scheme that offers lower access delay and packet loss rate, yet achieves a higher overall network throughput. We formulate a model for determining the traffic burstiness-dependent optimum prediction order that would enhance the quality of prediction with a minimum possible prediction-related processing overhead. We then demonstrate that, in a multi-class access scheduling, with respect to the conventional dynamic allocation strategies, our priority scheduling with judicious prediction of individual traffic classes can enhance the system performance significantly. Our analytic observations are supported by extensive simulation results.

International Dynamic Asset Allocation and Return Predictability

Abstract: The presence of time varying investment opportunity sets has been documented in the context of international asset allocation, and the economic value associated with these is a topic of lively debate in the academic literature. This paper constructs simple, real‐time dynamic international asset allocation strategies based on daily data that exploit the return predictability arising from time varying market integration. Our timing strategies outperform the major (US, UK, Japanese and German) country indices and related portfolios, particularly in down markets. The strategies appear to capture much of the economic value of the return predictability implied by market integration and have many of the characteristics of successful timing strategies.

Dynamic Memory Computation of Impedance Matrix Method

The computational efficiency of the impedance matrix method has been greatly improved for large pipe networks with various dimensions and complexity. Several numerical methods for solving linear system were modified to deal with the complex domain operation and used into impedance evaluation. Two different memory reduction schemes were developed based on one-dimensional storage and implemented with the biconjugate gradient method and the Gaussian elimination scheme, respectively. A new implementation of the impedance matrix method, namely, the dynamic memory allocation scheme, was introduced to efficiently model hydraulic transients in pipeline systems that have large topological structures. Three hypothetical pipe networks, the multiseries system, the multilooped system, and the multiblock system, were used to test the performance of the developed schemes. The impact of randomizing pipeline parameters, i.e., friction factor, length, and wave speed, on computation efficiency was evaluated and compared. The dynamic memory allocation scheme not only reduces costs substantially in CPU execution time and memory space compared to other schemes but also shows significant potential as a real-time unsteady flow predictor for large pipe networks.

Adaptive Self-Learning Resource Allocation Scheme for Unlicensed Users in High-Rate UWB Systems

In this paper, we investigate a dynamic sub-band allocation for spectrum sharing in the multiuser OFDM-UWB systems while respecting the system constraints and the distributed MAC architecture. The contribution of this work is twofold: first we propose a dynamic spectrum allocation scheme based on an analytical study by deriving a multiuser optimization problem to find the optimal allocation solution. Based on an adaptive and low-complexity approach, the proposed scheme shares the available resources among unlicensed UWB users while taking into consideration the QoS requirements and the channel conditions. Then we extend the proposed scheme to allow the coexistence of a maximum number of secondary users in one channel while maintaining all the constraints support. This leads to a time-frequency allocation approach that exploits information laying in different layers, allowing a cross-layer design. This new approach improves the system performance compared to WiMedia solution and offers a considerable gain for users that have strict QoS requirements.