An Architecture for Distributed Energies Trading in Byzantine-Based Blockchain

With the development of smart cities, not only are all corners of the city connected to each other, but also connected from city to city. They form a large distributed network together, which can facilitate the integration of distributed energy station (DES) and corresponding smart aggregators. Nevertheless, because of potential security and privacy protection arisen from trustless energies trading, how to make such energies trading goes smoothly is a tricky challenge. In this paper, we propose a blockchain-based multiple energies trading (B-MET) system for secure and efficient energies trading by executing a smart contract we design. Because energies trading requires the blockchain in B-MET system to have high throughput and low latency, we design a new byzantine-based consensus mechanism (BCM) based on node's credit to improve efficiency for the consortium blockchain under the B-MET system. Then, we take combined heat and power (CHP) system as a typical example that provides distributed energies. We quantify their utilities, and model the interactions between aggregators and DESs in a smart city by a novel multi-leader multi-follower Stackelberg game. It is analyzed and solved by reaching Nash equilibrium between aggregators, which reflects the competition between aggregators to purchase energies from DESs. In the end, we conduct plenty of numerical simulations to evaluate and verify our proposed model and algorithms, which demonstrate their correctness and efficiency completely

A k-hop Collaborate Game Model: Extended to Community Budgets and Adaptive Non-Submodularity

Revenue maximization (RM) is one of the most important problems on online social networks (OSNs), which attempts to find a small subset of users in OSNs that makes the expected revenue maximized. It has been researched intensively before. However, most of exsiting literatures were based on non-adaptive seeding strategy and on simple information diffusion model, such as IC/LT-model. It considered the single influenced user as a measurement unit to quantify the revenue. Until Collaborate Game model appeared, it considered activity as a basic object to compute the revenue. An activity initiated by a user can only influence those users whose distance are within k-hop from the initiator. Based on that, we adopt adaptive seed strategy and formulate the Revenue Maximization under the Size Budget (RMSB) problem. If taking into account the product's promotion, we extend RMSB to the Revenue Maximization under the Community Budget (RMCB) problem, where the influence can be distributed over the whole network. The objective function of RMSB and RMCB is adatpive monotone and not adaptive submodular, but in some special cases, it is adaptive submodular. We study the RMSB and RMCB problem under both the speical submodular cases and general non-submodular cases, and propose RMSBSolver and RMCBSolver to solve them with strong theoretical guarantees, respectively. Especially, we give a data-dependent approximation ratio for RMSB problem under the general non-submodular cases. Finally, we evaluate our proposed algorithms by conducting experiments on real datasets, and show the effectiveness and accuracy of our solutions

Differential Privacy-Based Online Allocations towards Integrating Blockchain and Edge Computing

In recent years, the blockchain-based Internet of Things (IoT) has been researched and applied widely, where each IoT device can act as a node in the blockchain. However, these lightweight nodes usually do not have enough computing power to complete the consensus or other computing-required tasks. Edge computing network gives a platform to provide computing power to IoT devices. A fundamental problem is how to allocate limited edge servers to IoT devices in a highly untrustworthy environment. In a fair competition environment, the allocation mechanism should be online, truthful, and privacy safe. To address these three challenges, we propose an online multi-item double auction (MIDA) mechanism, where IoT devices are buyers and edge servers are sellers. In order to achieve the truthfulness, the participants' private information is at risk of being exposed by inference attack, which may lead to malicious manipulation of the market by adversaries. Then, we improve our MIDA mechanism based on differential privacy to protect sensitive information from being leaked. It interferes with the auction results slightly but guarantees privacy protection with high confidence. Besides, we upgrade our privacy-preserving MIDA mechanism such that adapting to more complex and realistic scenarios. In the end, the effectiveness and correctness of algorithms are evaluated and verified by theoretical analysis and numerical simulations

Impact of Bt Cotton on the Farmer's Livelihood System in China

In order to analyze the impacts of Bt cotton on the farmers' livelihood system, we interviewed 169 farmers and extension personnel in the main cotton production areas in Hebei province in the year 2002 and 2003. An integrative method was used in which a multidisciplinary approach was employed including agronomy, economics and sociology. The results showed that the application of Bt cotton increased the cotton growing area as well as farmers' income. For 67% of the farmers interviewed, cotton area has been continuously increasing since 1997. The cotton net margin in one cropping cycle came out to be higher than the combined net margins of wheat and corn in two cropping cycles. The income from cotton played a significant role in the investment to education, leisure and health care. The socio-economic impacts of cotton production are nevertheless not yet optimal because there were still many factors limiting them. Lack of labor and land were the main limiting factors. Productivity is restrained by the high price of Bt cotton seeds which pushed farmers to keep seeds from their own cotton production (42% of the farmers in 2002 and 2003). Farmers are still lacking technical command in using Bt-cotton: 78% of the farmers admitted that while more than 94% of the farmers complained not getting information from local extension and technical services. More success in using Bt-cotton calls upon going beyond providing seeds and asks for continuous assistance from research and extension department, notably to achieve a full knowledge of the Bt-cotton characteristic so as to optimally integrate it into the farmers' system.China; Bt Cotton; biotechnologies; impact evaluation; Livelihood