946 research outputs found
Distributed Optimal Rate-Reliability-Lifetime Tradeoff in Wireless Sensor Networks
The transmission rate, delivery reliability and network lifetime are three
fundamental but conflicting design objectives in energy-constrained wireless
sensor networks. In this paper, we address the optimal
rate-reliability-lifetime tradeoff with link capacity constraint, reliability
constraint and energy constraint. By introducing the weight parameters, we
combine the objectives at rate, reliability, and lifetime into a single
objective to characterize the tradeoff among them. However, the optimization
formulation of the rate-reliability-reliability tradeoff is neither separable
nor convex. Through a series of transformations, a separable and convex problem
is derived, and an efficient distributed Subgradient Dual Decomposition
algorithm (SDD) is proposed. Numerical examples confirm its convergence. Also,
numerical examples investigate the impact of weight parameters on the rate
utility, reliability utility and network lifetime, which provide a guidance to
properly set the value of weight parameters for a desired performance of WSNs
according to the realistic application's requirements.Comment: 27 pages, 10 figure
Business Borderlands: China's Overseas State Agribusiness
In the context of widespread interests in China's agro?state?owned enterprises (SOEs), this article starts demystifying four narratives prevailing internationally. In this intellectual landscape, the article coins an innovative approach, ‘farm as business borderland’ to investigate an agro?SOE in Tanzania. Based on the ethnographic case study, the article presents the tensions arising between the case farm and its Beijing headquarters on the one hand, and between Chinese managers and local stakeholders on the other. The authors examine the reasons why the travelling business bureaucracy rationalities from Beijing to Tanzania works and how this is adapted locally in the farm's daily practices. The authors also explore why and how Chinese managers' footloose expatriate lifestyle is not as relevant as normally expected in constructing convergence with locals. Finally the article discusses the implications of the new approach on international development inquiry and global governance practices
Universal Soldier: Using Universal Adversarial Perturbations for Detecting Backdoor Attacks
Deep learning models achieve excellent performance in numerous machine
learning tasks. Yet, they suffer from security-related issues such as
adversarial examples and poisoning (backdoor) attacks. A deep learning model
may be poisoned by training with backdoored data or by modifying inner network
parameters. Then, a backdoored model performs as expected when receiving a
clean input, but it misclassifies when receiving a backdoored input stamped
with a pre-designed pattern called "trigger". Unfortunately, it is difficult to
distinguish between clean and backdoored models without prior knowledge of the
trigger. This paper proposes a backdoor detection method by utilizing a special
type of adversarial attack, universal adversarial perturbation (UAP), and its
similarities with a backdoor trigger. We observe an intuitive phenomenon: UAPs
generated from backdoored models need fewer perturbations to mislead the model
than UAPs from clean models. UAPs of backdoored models tend to exploit the
shortcut from all classes to the target class, built by the backdoor trigger.
We propose a novel method called Universal Soldier for Backdoor detection (USB)
and reverse engineering potential backdoor triggers via UAPs. Experiments on
345 models trained on several datasets show that USB effectively detects the
injected backdoor and provides comparable or better results than
state-of-the-art methods
Mining frequent sequences using itemset-based extension
In this paper, we systematically explore an itemset-based extension approach for generating candidate sequence which contributes to a better and more straightforward search space traversal performance than traditional item-based extension approach. Based on this candidate generation approach, we present FINDER, a novel algorithm for discovering the set of all frequent sequences. FINDER is composed oftwo separated steps. In the first step, all frequent itemsets are discovered and we can get great benefit from existing efficient itemset mining algorithms. In the second step, all frequent sequcnces with at least two frequent itemsets are detected by combining depth-first search and item set-based extension candidate generation together. A vertical bitmap data representation is adopted for rapidly support counting reason. Several pruning strategies are used to reduce the search space and minimize cost of computation. An extensive set ofexperiments demonstrate the effectiveness and the linear scalability of proposed algorithm
The archaeal ATPase PINA interacts with the helicase Hjm via its carboxyl terminal KH domain remodeling and processing replication fork and Holliday junction.
PINA is a novel ATPase and DNA helicase highly conserved in Archaea, the third domain of life. The PINA from Sulfolobus islandicus (SisPINA) forms a hexameric ring in crystal and solution. The protein is able to promote Holliday junction (HJ) migration and physically and functionally interacts with Hjc, the HJ specific endonuclease. Here, we show that SisPINA has direct physical interaction with Hjm (Hel308a), a helicase presumably targeting replication forks. In vitro biochemical analysis revealed that Hjm, Hjc, and SisPINA are able to coordinate HJ migration and cleavage in a concerted way. Deletion of the carboxyl 13 amino acid residues impaired the interaction between SisPINA and Hjm. Crystal structure analysis showed that the carboxyl 70 amino acid residues fold into a type II KH domain which, in other proteins, functions in binding RNA or ssDNA. The KH domain not only mediates the interactions of PINA with Hjm and Hjc but also regulates the hexameric assembly of PINA. Our results collectively suggest that SisPINA, Hjm and Hjc work together to function in replication fork regression, HJ formation and HJ cleavage
Numerical simulation of secondary breakup of shear-thinning droplets
The breakup of non-Newtonian droplets is ubiquitous in numerous applications.
Although the non-Newtonian property can significantly change the droplet
breakup process, most previous studies consider Newtonian droplets, and the
effects of the non-Newtonian properties on the breakup process are still
unclear. This study focuses on the secondary breakup of shear-thinning droplets
by numerical simulation. The volume of fluid method is used to capture
interface dynamics on adaptive grids. To compare shear-thinning droplets and
Newtonian droplets, a new definition of the Ohnesorge number is proposed by
considering the characteristic shear rate in the droplet induced by the
airflow. The results show that compared with the Newtonian fluid, the
shear-thinning properties can change the effective viscosity distribution
inside the droplet, alter the local deformation, change the droplet morphology,
and affect the transition in the droplet breakup regime.Comment: 14 pages, 15 figure
Wireless Network Digital Twin for 6G: Generative AI as A Key Enabler
Digital twin, which enables emulation, evaluation, and optimization of
physical entities through synchronized digital replicas, has gained
increasingly attention as a promising technology for intricate wireless
networks. For 6G, numerous innovative wireless technologies and network
architectures have posed new challenges in establishing wireless network
digital twins. To tackle these challenges, artificial intelligence (AI),
particularly the flourishing generative AI, emerges as a potential solution. In
this article, we discuss emerging prerequisites for wireless network digital
twins considering the complicated network architecture, tremendous network
scale, extensive coverage, and diversified application scenarios in the 6G era.
We further explore the applications of generative AI, such as transformer and
diffusion model, to empower the 6G digital twin from multiple perspectives
including implementation, physical-digital synchronization, and slicing
capability. Subsequently, we propose a hierarchical generative AI-enabled
wireless network digital twin at both the message-level and policy-level, and
provide a typical use case with numerical results to validate the effectiveness
and efficiency. Finally, open research issues for wireless network digital
twins in the 6G era are discussed
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