State of the art technologies like air-to-water heat pumps have become popular because of their high efficiencies and their supply by electricity rather than by gas or oil. As a direct result of this supply substituti...
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State of the art technologies like air-to-water heat pumps have become popular because of their high efficiencies and their supply by electricity rather than by gas or oil. As a direct result of this supply substitution and due to high load- shifting potential, electricity demand of heat pumps have to be taken into account into energy management strategies of the overall building. In this paper a new controller is discussed, which has predictive and adaptive properties and is able to optimize the running-times of non-modulating heat pumps.
A new robust digital watermarking technique with an aim of image protection is proposed. This technique incorporates both the transform and feature based method. Initially, the Harris Laplacian detector extracts the f...
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ISBN:
(纸本)9781479979868
A new robust digital watermarking technique with an aim of image protection is proposed. This technique incorporates both the transform and feature based method. Initially, the Harris Laplacian detector extracts the features from the cover image that suites well for the watermarking. The extracted characteristic regions are grouped to form a primary feature set where the secret message is embedded to form a watermarked image. This image is tested by introducing six different predefined attacks, which checks the robustness of the extracted feature. DCT transformation method extracts the secret message from the watermarked image. According to the results, the watermarked image is vulnerable to the undefined attack. To enhance the resistance against those attacks the primary feature set is extended by adding some auxiliary features. These features are extracted through knapsack algorithm. The watermark is embedded into these auxiliary features where the secret message is not affected by any attacks. The experimental results show that the proposed watermark technique is efficient and also preserves the image quality.
The article mainly researches task scheduling algorithm based on Map Reduce in cloud computing, presents a Two-circle task scheduling algorithm based on Map Reduce, uses Weighted Round Robin in the first circle,and ev...
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The article mainly researches task scheduling algorithm based on Map Reduce in cloud computing, presents a Two-circle task scheduling algorithm based on Map Reduce, uses Weighted Round Robin in the first circle,and every task was executed in turn withen the cycle, assign more time slice on some tasks that can complete for more time,according to weighted value;Tasks execute based on knapsack theory in the second circle, namely perform more tasks with fixed times, short task,local task and task can be easy to implement will execute with priority, if there is no such task, we select task that timevalue ratio is high to execute. So we can improve the efficiency of the original scheduling algorithm, taking into account the fairness of job execution, improve response time for short jobs, local jobs and job that is easy to implement.
The use of virtualization technology (VT) has become widespread in modern datacenters and Clouds in recent years. In spite of their many advantages, such as provisioning of isolated execution environments and migratio...
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The use of virtualization technology (VT) has become widespread in modern datacenters and Clouds in recent years. In spite of their many advantages, such as provisioning of isolated execution environments and migration, current implementations of VT do not provide effective performance isolation between virtual machines (VMS) running on a physical machine (PM) due to workload interference of VMs. Generally, this interference is due to contention on physical resources that impacts performance in different workload configurations. To investigate the impacts of this interference, we formalize the concept of interference for a consolidated multi-tenant virtual environment. This formulation, represented as a mathematical model, can be used by schedulers to estimate the interference of a consolidated virtual environment in terms of the processing and networking workloads of running VMs, and the number of consolidated VMs. Based on the proposed model, we present a novel batch scheduler that reduces the interference of running tenant VMs by pausing VMs that have a higher impact on proliferation of the interference. The scheduler achieves this by selecting a set of VMs that produce the least interference using a 0-1 knapsack problem solver. The selected VMs are allowed to run and other VMs are paused. Users are not troubled by the pausing and resumption of VMs for a short time because the scheduler has been designed for the execution of batch type applications such as scientific applications. Evaluation results on the makespan of VMs executed under the control of our scheduler have shown nearly 33% improvement in the best case and 7% improvement in the worst case compared to the case in which all VMs are running concurrently. In addition, the results show that our scheduling algorithm outperforms serial and random scheduling of VMs as well. (C) 2013 Elsevier B.V. All rights reserved.
Enhancing security is the main intention for public key cryptosystems on the basis of the hardness of the obstinate computational problems. In this paper, the ASCII value depiction of the text message is mapped into a...
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Enhancing security is the main intention for public key cryptosystems on the basis of the hardness of the obstinate computational problems. In this paper, the ASCII value depiction of the text message is mapped into a point on elliptic curve and this initiates a few order of complexity yet before the message is encrypted. Next, the process of encryption/decryption of a mapped elliptic curve point is illustrated by enhancing security using comparative linear congruential generator and then subjecting it to the knapsack algorithm. These steps introduce scrupulous confusion and diffusion to smash any attempt at brute force attacks. This paper also discusses the security aspects of the proposed cryptosystem which is secure against all kinds of attacks.
We present a provably-good distributed algorithm for generalized task assignment problem in the context of multirobot systems, where robots cooperate to complete a set of given tasks. In multi-robot generalized assign...
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ISBN:
(纸本)9781467363563
We present a provably-good distributed algorithm for generalized task assignment problem in the context of multirobot systems, where robots cooperate to complete a set of given tasks. In multi-robot generalized assignment problem (MR-GAP), each robot has its own resource constraint (e.g., energy constraint), and needs to consume a certain amount of resource to obtain a payoff for each task. The objective is to find a maximum payoff assignment of tasks to robots such that each task is assigned to at most one robot while respecting robots' resource constraints. MR-GAP is a NP-hard problem. It is an extension of multi-robot linear assignment problem since different robots can use different amount of resource for doing a task (due to the heterogeneity of robots and tasks). We first present an auction-based iterative algorithm for MR-GAP assuming the presence of a shared memory (or centralized auctioneer), where each robot uses a knapsack algorithm as a subroutine to iteratively maximize its own objective (using a modified payoff function based on an auxiliary variable, called price of a task). Our iterative algorithm can be viewed as (an approximation of) best response assignment update rule of each robot to the assignment of other robots at that iteration. We prove that our algorithm converges to an assignment (approximately) at equilibrium under the assignment update rule, with an approximation ratio of 1 + α (where α is the approximation ratio for the knapsack problem). We also combine our algorithm with a message passing mechanism to remove the requirement of a shared memory and make our algorithm totally distributed assuming the robots' communication network is connected. Finally, we present simulation results to depict our algorithm's performance.
We consider the design of the revenue maximizing mechanism for a seller with a fixed capacity of C units selling over T periods to buyers who arrive over time. The buyers have single unit demand and multi-dimensional ...
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ISBN:
(纸本)9781611972511
We consider the design of the revenue maximizing mechanism for a seller with a fixed capacity of C units selling over T periods to buyers who arrive over time. The buyers have single unit demand and multi-dimensional private information- both their value for the object and the deadline by which they must make a purchase are unknown to the seller. This contrasts with previous work where buyers have single dimensional private information- deadlines are publicly observed and only values are private. Here, the optimal mechanism can be computed by running a dynamic stochastic knapsack algorithm. However, these mechanisms are only optimal with private deadlines when the calculated allocation rule is monotone- buyers with higher values and later deadlines should be allocated with higher probability. Such monotonicity only arises in very special cases. By contrast, in the classic static environment of Myerson monotonicity is only violated for 'irregular' value distributions. Myerson characterizes the optimal mechanism by a procedure he calls 'ironing.' We characterize the optimal mechanism in our general dynamic environment by providing the dynamic counterpart of ironing. We show that only a subset of the monotonicity constraints can bind in a solution of the seller's dynamic programming problem. The optimal mechanism can be characterized by 'relaxing' these constraints with their appropriate dual multiplier. Further, the optimal mechanism can be implemented by a series of posted prices followed by a 'biased' auction in the final period where buyers have the auction biased in their favor depending on their arrival time. Our theoretical characterization complements the existing computational approaches for ironing in these settings (e.g. Parkes et al.).
Assessing the environmental impacts of agricultural practices at the catchment scale increasingly involves the use of spatially distributed models that include cropping systems as input. Use of these models for diagno...
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Assessing the environmental impacts of agricultural practices at the catchment scale increasingly involves the use of spatially distributed models that include cropping systems as input. Use of these models for diagnosis and evaluation requires large datasets at large spatial and temporal scales. The description of spatial dynamics of cropping systems at a fine resolution (i.e. field level) is particularly needed. As these data are scarce or not available, our objective was to propose a model that first reconstructs spatial dynamics of past cropping systems from available data, and second constructs alternative spatial cropping systems, corresponding to agricultural practice scenarios. Classification systems for farms and fertilisation practices were defined to classify farm-level organisation for crop-succession and crop management strategies, in particular nitrogen fertilisation. Winter cover crops and multiple strategies per crop at the farm level can be represented with this model. Cropping systems are modelled in three steps: we modelled crop cover succession in summer with Markov chains based on empirical data and in winter with rules based on expert agronomic knowledge: lastly a knapsack-based algorithm was used to allocate a crop management system to fields with constraints on several crop management strategies per crop type. Results of a case study performed on the Fremeur catchment (western France) show that this model respects the main constraints for cropping system modelling to assess agricultural practices at the catchment scale. From a scenario discussed with stakeholders and regional authorities characterised by stable areas of summer crops, the decrease in bare soil area in winter and overall reduction in total nitrogen fertilisation for different types of crops and farms we demonstrate the model's ability to simulate coherent cropping systems. Thus, if faced with a lack of data or knowledge about the local factors that drive changes in cropping sys
Elliptic curve cryptography (ECC) provides a secure means of exchanging keys among communicating hosts using the Diffie Hellman key exchange algorithm. Encryption and decryption of texts and messages have also been at...
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Elliptic curve cryptography (ECC) provides a secure means of exchanging keys among communicating hosts using the Diffie Hellman key exchange algorithm. Encryption and decryption of texts and messages have also been attempted. This paper presents the ECC implementation for digital signature authentication and then applying the knapsack algorithm on ECC signing message. In this paper, we attempt to provide more secure digital signature scheme by using knapsack based ECC. We compare our proposed algorithm with RSA based digital signature authentication algorithm and show that our algorithm is better due to the high degree of sophistication and complexity involved. It is almost infeasible to attempt a brute force attack. Moreover, only one parameter namely the knapsack vector ai needs to be kept secret. On the contrary in RSA, three parameters such as the modulus n, its factors p and q need to be kept secret.
The paper describes Greedy algorithm, the knapsack problem and it's their related theory, In Order to achieve the greatest scope of students benefits and improving the efficiency of the use of the laboratory, It p...
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ISBN:
(纸本)9780769537290
The paper describes Greedy algorithm, the knapsack problem and it's their related theory, In Order to achieve the greatest scope of students benefits and improving the efficiency of the use of the laboratory, It puts forward a dynamic programming algorithm of the three value models based on Greedy algorithm. Via the combined value of three model and weight proportion parameter settings, the relevant sorting algorithm and search algorithm, the way achieves an effective approximation of the overall optimization and coordinates the various objects possible conflict.
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