A Blockchain-Based Tamper-Resistant Logging Framework

Since its introduction in Bitcoin, the blockchain has proven to be a versatile data structure. In its role as an immutable ledger, it has grown beyond its initial use in financial transactions to be used in recording a wide variety of other useful information. In this paper, we explore the application of the blockchain outside of its traditional decentralized, financial domain. We show how, even with only a single “mining” node, a proof-of-work blockchain can be the cornerstone of a tamper resistant logging framework. By attaching a proof-of-work to blocks of logging messages, we make it increasingly difficult for an attacker to modify those logs even after totally compromising the system. Furthermore, we discuss various strategies an attacker might take to modify the logs without detection and show how effective those evasion techniques are against statistical analysis

Crowdfunding Non-fungible Tokens on the Blockchain

Non-fungible tokens (NFTs) have been used as a way of rewarding content creators. Artists publish their works on the blockchain as NFTs, which they can then sell. The buyer of an NFT then holds ownership of a unique digital asset, which can be resold in much the same way that real-world art collectors might trade paintings. However, while a deal of effort has been spent on selling works of art on the blockchain, very little attention has been paid to using the blockchain as a means of fundraising to help finance the artist’s work in the first place. Additionally, while blockchains like Ethereum are ideal for smaller works of art, additional support is needed when the artwork is larger than is feasible to store on the blockchain. In this paper, we propose a fundraising mechanism that will help artists to gain financial support for their initiatives, and where the backers can receive a share of the profits in exchange for their support. We discuss our prototype implementation using the SpartanGold framework. We then discuss how this system could be expanded to support large NFTs with the 0Chain blockchain, and describe how we could provide support for ongoing storage of these NFTs

Effect of Dietary Aluminum Sulfate on Calcium and Phosphorus Metabolism of Broiler Chicks

The effect of dietary aluminum sulfate on Ca and P metabolism was studied using 1-day-oldmale broiler chicks. In Experiment 1, practical diets providing .90% Ca plus .45% available P (Pav), .90% Ca plus .78% Pav, 1.80% Ca plus .45% Pav, or 1.80% Ca plus .90% Pav were fed with 0 or .392% Al as aluminum sulfate for 21 days. The control diet (.90% Caplus .45% Pav) without added A1 was fed to all chicks during Days 22 to 49. In general, Al significantly (Pi), tibia breaking strength, tibia weight, percentage of tibia ash, and plasma Zn, measured at Day 21. Elevating Pav increased BW gain, feed intake, gain:feed ratio, tibia weight and plasma Zn, and decreased plasma total Ca in the presence of .392% Al plus 1.80% Ca. Plasma Pi, tibia breaking strength, and percentage of tibia ash were increased by raising dietary Pav in the presence of .392% Al with either level of Ca. Negative effects of dietary Al on feed intake and BW persisted through Day 49. In Experiment 2, a control diet (.90% Ca, .45% Pav) was fed for ad libitum access either alone or supplemented with .2% Al as aluminum sulfate or with an equivalent amount of sulfate provided by potassium sulfate. The control diet was also pair-fed to chicks given .2% Al. Dietary Al significantly depressed weight gain, feed intake, gain:feed ratio, and plasma Pi. No effects were noted due to adding potassium sulfate to the diet. Pair-feeding the control diet decreased weight gain, feed intake, and tibia weight, but not plasma Pi. These results indicate that the toxic effect of aluminum sulfate is due to the aluminum and not the sulfate ions. The influence of aluminum on growth is mainly due to depressed feed intake, while the altered Ca and P metabolism results from a direct effect of Al per se

Semiconductor-based Multilayer Selective Solar Absorber for Unconcentrated Solar Thermal Energy Conversion

Solar thermal energy conversion has attracted substantial renewed interest due to its applications in industrial heating, air conditioning, and electricity generation. Achieving stagnation temperatures exceeding 200 °C, pertinent to these technologies, with unconcentrated sunlight requires spectrally selective absorbers with exceptionally low emissivity in the thermal wavelength range and high visible absorptivity for the solar spectrum. In this Communication, we report a semiconductor-based multilayer selective absorber that exploits the sharp drop in optical absorption at the bandgap energy to achieve a measured absorptance of 76% at solar wavelengths and a low emittance of approximately 5% at thermal wavelengths. In field tests, we obtain a peak temperature of 225 °C, comparable to that achieved with state-of-the-art selective surfaces. With straightforward optimization to improve solar absorption, our work shows the potential for unconcentrated solar thermal systems to reach stagnation temperatures exceeding 300 °C, thereby eliminating the need for solar concentrators for mid-temperature solar applications such as supplying process heat

Relationship of Dietary Aluminum, Phosphorus, and Calcium to Phosphorus and Calcium Metabolism and Growth Performance of Broiler Chicks

Dietary treatments providing three levels of added Al (0, .196, or .392%) as aluminum sulfate and of available phosphorus (Pav) (.45, .68, or .78%) in a factorial arrangement were administered to day-old chicks in Experiment 1. Plasma inorganic phosphorus (Pi) was significantly (P \u3c .05) elevated by increasing Pav and was decreased by Al. Body weight gain, feed intake, and the gain:feed ratio at Day 21 were significantly decreased by increased concentrations of Al, but were unaffected by the Pav concentrations. Decreases of 39 and 73% in weight gain and of 34 and 66% in feed intake resulted from feeding .196 and .392% AL respectively. In Experiment 2, day-old chicks were fed diets supplemented with 0 or .392% Al in combination with .9% Ca plus .45% Pav, .9% Ca plus .78% Pav, 1.8% Ca plus .45% Pav, or 1.8% Caplus .9% Pav. After 21 days, the supplemental A1 resulted in: 1) significantly poorer growth performance; 2) decreased plasma Pi, total Ca, Zn, and Mg; and 3) decreased tibia weight and breaking strength. Elevating Pav improved growth performance, plasma Pi, and tibia weight and strength, and decreased plasma total Ca. Increasing dietary Ca significantly decreased plasma Pi and increased plasma total Ca without affecting other parameters. Increasing Pav alleviated the negative effect of Al on plasma Pi without correcting the negative effect of Al on growth performance

Attitude Determination and Control System With Variable-Speed Single-Gimbal Control Moment Gyroscopes for Nanosatellites

This paper presents a novel Attitude Determination and Control System (ADCS) utilizing Variable-Speed Control Moment Gyroscopes (VSCMG) tailored explicitly for nanosatellites. The VSCMG was realized by spherical motor technology, in which a patented magnetic field design controls the inner rotor and gimbal. Because of the characteristics of the control moment gyroscope, the proposed ADCS offers improved attitude maneuverability and reduced power consumption, addressing the limitations of traditional ADCS solutions for nanosatellites. Furthermore, the adoption of spherical motor technology shrinks the VSCMG into a smaller form factor, which allows the VSCMG to be fitted into a nanosatellite. This research paper introduces the specifications of the integrated ADCS family based on VSCMG, as well as the components used in the system

Electronic Modulation of Near-Field Radiative Transfer in Graphene Field Effect Heterostructures

Manipulating heat flow in a controllable and reversible manner is a topic of fundamental and practical interest. Numerous approaches to perform thermal switching have been reported, but they typically suffer from various limitations, for instance requiring mechanical modulation of a submicron gap spacing or only operating in a narrow temperature window. Here, we report the experimental modulation of radiative heat flow by electronic gating of a graphene field effect heterostructure without any moving elements. We measure a maximum heat flux modulation of 4 ± 3% and an absolute modulation depth of 24 ± 7 mW m^(–2) V^(–1) in samples with vacuum gap distances ranging from 1 to 3 μm. The active area in the samples through which heat is transferred is ∼1 cm^2, indicating the scalable nature of these structures. A clear experimental path exists to realize switching ratios as large as 100%, laying the foundation for electronic control of near-field thermal radiation using 2D materials

Attitude Control Calibration and Experiment Testbed to Characterize Attitude Determination and Control System Performance

This paper describes the design, development, and construction of an attitude control testbed to investigate the performance of ADCS. The Testbed consists of three instruments, an air-bearing platform, a Helmholtz cage, and an AM0 spectrum solar simulator. The Testbed in this research features the capability to measure the mass properties of the tested satellite. One of the motivations of this paper is to share the experience while building this highly automated Testbed. Finally, the procedure of the mass properties measurement will be well described in this paper

Access Control for Plugins in Cordova-Based Hybrid Applications

Hybrid application frameworks such as Cordova allow mobile application (app) developers to create platformindependent apps. The code is written in JavaScript, with special APIs to access device resources in a platform-agnostic way. In this paper, we present a novel app-repackaging attack that repackages hybrid apps with malicious code; this code can exploit Cordova’s plugin interface to tamper with device resources. We further demonstrate a defense against this attack through the use of a novel runtime access control mechanism that restricts access based on the mobile user’s judgement. Our mechanism is easy to introduce to existing Cordova apps, and allows developers to produce apps that are resistant to app-repackaging attacks