The traditional models of land suitability evaluation were short of comprehensive considering land use with natural,
social and economic characters. In this paper, the model of land eco-economic suitability evaluation was constructed
based on niche suitability, which is to say that the evaluation is to match the land resource real niche with the demanding
niche of life. Then a case study is taken to demonstrate the rationality and validity of the model.
Using the optimization result of landscape pattern and land use structure optimization as constraints of CA simulation
results, a decision-making model of land use spatial optimization is established coupled the landscape pattern model with
cellular automata to realize the land use quantitative and spatial optimization simultaneously. And Huangpi district is
taken as a case study to verify the rationality of the model.
Uncertainty management has been considered essential for physical world application especially uncertain spatial
relation representation and reasoning for Geographic Information System applications. In this paper a unified space
partition and identical operator for uncertain topological and directional relation representation and reasoning are
proposed, and an integrated model is constructed. Then the workflow of the reasoning is designed with using the model.
At last a case studies are taken, which results demonstrate the rationality and viability of the model for uncertain
topological and directional reasoning.
Class-based service differentiation is provided in DiffServ networks. However, this differentiation will be disordered under dynamic traffic loads due to the fixed weighted scheduling. An adaptive weighted scheduling scheme is proposed in this paper to achieve fair bandwidth allocation among different service classes. In this scheme, the number of active flows and the subscribed bandwidth are estimated based on the measurement of local queue metrics, then the scheduling weights of each service class are adjusted for the per-flow fairness of excess bandwidth allocation. This adaptive scheme can be combined with any weighted scheduling algorithm. Simulation results show that, comparing with fixed weighted scheduling, it effectively improve the fairness of excess bandwidth allocation.
This paper analyzes a communication network facing users with a continuous distribution of delay cost per unit time. Priority queueing is often used as a way to provide differential services for users with different delay sensitivities. Delay is a key dimension of network service quality, so priority is a valuable resource which is limited and should to be optimally allocated. We investigate the allocation of priority in queues via a simple bidding mechanism. In our mechanism, arriving users can decide not to enter the network at all or submit an announced delay sensitive value. User entering the network obtains priority over all users who make lower bids, and is charged by a payment function which is designed following an exclusion compensation principle. The payment function is proved to be incentive compatible, so the equilibrium bidding behavior leads to the implementation of “cμ-rule”. Social warfare or revenue maximizing by appropriately setting the reserve payment is also analyzed.
Multicast is an efficient approach to save network bandwidth for multimedia streaming services. To provide Quality of Services (QoS) for the multimedia services while maintain the advantage of multicast in bandwidth efficiency, admission control for multicast sessions are expected. Probe-based multicast admission control (PBMAC) schemes are of a sort of scalable and simple admission control for multicast. Probing scheme is the essence of PBMAC. In this paper, after a detailed survey on three existing probing schemes, we evaluate these schemes using simulation and analysis approaches in two aspects: admission correctness and group scalability. Admission correctness of the schemes is compared by simulation investigation. Analytical models for group scalability are derived, and validated by simulation results. The evaluation results illustrate the advantages and weaknesses of each scheme, which are helpful for people to choose proper probing scheme for network.
As the channel is accessed randomly in IEEE 802.11 WLAN systems, it’s difficult to support Quality of Services for real time applications. To solve the issue, there are already some approaches proposed in different network layers. However, when those QoS approaches are implemented in different network environments, the performance may vary significantly. In this paper, we will compare two major classes of QoS schemes for IEEE 802.11 WLAN in MAC layer and network layer respectively. The performances are compared in both one hop and multi-hop ad hoc network environments. It’s observed that MAC layer QoS scheme is very efficient in one hop network environments, while network layer QoS schemes is only efficient for multi-hop ad hoc networks. Based on the observations, it’s necessary to design a new hybrid scheme to efficiently support QoS in IEEE 802.11 WLAN system.
This paper studies landuse change model based on cellar automata of decision-making with grey situation. the urban land use dynamic change model is constructed based on decision-making with gray situation and hierarchical method as well as CA, in which the hierarchical method is used for dealing with the importance of among objects and factors. The arable land is used as constraint factor for transformation rules in the model, Lastly, the model has been tested by taking Qionghai city of Hainan province as an example, the result shows that the model is valid for simulating urban landuse change.