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The development of the Internet of Things (IoT) technology has achieved remarkable results in recent years. A large number of sensors and machinery are connected, and combined with the Internet, to achieve intelligent management and operation. However, the traditional centralized IoT data management solution inevitably encounters challenges of data trust, security, sustainability, and user privacy is difficult to guarantee. This paper takes the intelligent transportation sensor network as an example and proposes a blockchain-based Internet of Vehicles (IoV) data secure sharing scheme (called IoVChain), which implements automatic registration, rapid authentication, and reliable sharing method of IoV data through smart contract. The smart contract performs homomorphic encryption and zero-knowledge proof processing on the sensitive part of the data, and this part exists in the form of ciphertext on the blockchain. We adopt PBFT consensus mechanism to ensure the consistency of the entire network ledger, and all the IoV data processing and usage procedure is stored in the Merkle-tree-based block, which cannot be tampered with. Compared with the centralized IoV data management solution, the IoVChain scheme avoids the risk of single point of failure, and keeps the IoV data credible, available, and tamper-resistant under the premise of privacy and security, so that the data can be traced when needed. We have implemented the IoVChain scheme based on the consortium blockchain for trusted and secure sharing of IoV data. Finally, analysis and evaluation show that the proposed IoVChain scheme is feasible, safe, and extensible for the secure sharing of IoV data.

The pathophysiological mechanisms of diabetic cardiomyopathy have been extensively studied, but there is still a lack of effective prevention and treatment methods. The ability of flavonoids to protect the heart from diabetic cardiomyopathy has been extensively described. In recent years, epigenetics has received increasing attention from scholars in exploring the etiology and treatment of diabetes and its complications. DNA methylation, histone modifications and non-coding RNAs play key functions in the development, maintenance and progression of diabetic cardiomyopathy. Hence, prevention or reversal of the epigenetic alterations that have occurred during the development of diabetic cardiomyopathy may alleviate the personal and social burden of the disease. Flavonoids can be used as natural epigenetic modulators in alternative therapies for diabetic cardiomyopathy. In this review, we discuss the epigenetic effects of different flavonoid subtypes in diabetic cardiomyopathy and summarize the evidence from preclinical and clinical studies that already exist. However, limited research is available on the potential beneficial effects of flavonoids on the epigenetics of diabetic cardiomyopathy. In the future, clinical trials in which different flavonoids exert their antidiabetic and cardioprotective effects through various epigenetic mechanisms should be further explored.

In this paper, an optimal scheduling method based on building virtual energy storage equivalent battery is proposed. Firstly, the thermal load prediction model is built based on the thermodynamic model, and then the equivalent battery model of virtual energy storage is established by combining with inverter air conditioning system model. Then, with the goal of minimizing the user’s electricity cost, considering the constraints of energy storage state and charging and discharging power of equivalent battery model, an optimal scheduling method of building virtual energy storage equivalent battery is constructed. The results show that the proposed method can predict the building thermal load, update the building virtual energy storage equivalent battery parameters, formulate the corresponding optimal scheduling strategy, and reduce the electricity cost of users for heating on the premise of ensuring the thermal comfort of users.

Asbestos is highly fire-resistant, and electrically and thermally insulating, and it is a type of important industrial material. At the same time, however, this type of substance is proven to be highly dangerously carcinogenic. Asbestos fiber is harmful to human health, and it is important to test the asbestos in products. There is no applicable specification available in our country for the method of determining the asbestos in Brake Pads. In this paper, one method of using a polarizing microscope with a X-ray diffraction is used to identify the asbestos. Firstly, the characteristic features of the specimen was obtained under a polarizing microscope, if any fibrous particle exists, further test will be made with the help of a X-ray diffraction. If the fiber under observation has asbestos diffraction peak, it will be initially determined that the fiber under observation is the asbestos fiber. Otherwise, it will be determined that the fiber under observation is not asbestos fiber particles, and no asbestos has been found in the specimens. The other method of using a scanning electron microscope with a X-ray diffractometer is used to identify the asbestos in automotive brake pads, and this method is simple, fast, reliable and suitable to be widely applied. And the result shows that this method of testing for asbestos in brake pads through polarizing microscope and X-ray diffraction or a scanning electron microscope and X-ray diffractometer are simple, reliable and suitable to be widely applied.

The efficiency and economic performance of the microgrid (MG) are significantly improved by the combined heat and power (CHP) unit. In this paper, an optimal scheduling method for the CHP-based MG based on model predictive control (MPC) is proposed. Based on the energy hub (EH) model, the model of CHP-based MG was presented. An optimal scheduling model whose purpose is to minimize the total cost for CHP based microgrid was proposed in this paper then. And the MPC method was applied to the optimal scheduling model to deal with the uncertainty of renewable energy in the MG. The method is applied to a typical CHP based microgrid to verify the effectiveness.

With the development of computing technology, the security and credibility of data is becoming more and more important. However, the security and trust of traditional centralized system is insufficient and data tampering is easy to occur, which leads to data distrustful. The characteristics of blockchain, such as traceable and tamper-proof, can solve the issue of data trust. However, the access threshold of the blockchain is high. In order to reduce the technical difficulty, in this article, a universal BaaS platform (called TrustedBaaS) which has high flexibility and scalability was designed based on consortium blockchain, it can support user-defined configuration according to requirements of users. Afterwards we described the process of executing a transaction in detail and discussed the core protocols and algorithms of the BaaS platform, which includes identity authentication, consensus algorithm, data protection protocol, smart contract and on-blockchain and off-blockchain data collaboration. Furthermore, we implemented TrustedBaaS based on Hyperledger Fabric and a vehicular information management application platform and a transaction settlement application platform were configured based on TrustedBaaS. Finally, we evaluated the performance of the TrustedBaaS and compared it with current public blockchain such as Bitcoin and Ethereum. The evaluation showed that the designed TrustedBaaS has better performance than the existing public blockchain platforms. Moreover, it is common distributed higher-level trusted platform which provides configurable and extensible functions and solves the problem that the access threshold of blockchain technology is high.

Polyacrylonitrile (PAN) fibers were stabilized continuously through a series of temperature zones, and the stabilized PAN fibers (SFs) taken out from different zones were irradiated with γ-ray, finally, some of the irradiated SFs were carbonized continuously. Structure changes of the SFs and mechanical properties of the derived carbon fibers were investigated. It is found that γ-ray not only could destroy the nitrile crosslinking bonds and form nitrile groups again in slight SFs, but could make more crosslinked structure including ether crosslinking and carbon-carbon crosslinking in slight and deep SFs, which improved thermal stability of the SFs and tensile strength of the carbon fibers. The irradiation also induced cyclization in short sequence in slight SFs, however, such a cyclization structure didn't significantly improve thermal stability.

Gamma ray irradiation on PAN fibers did bring some benefits for the successive stabilization, however, it is still unclear about the structure of crosslinked bonds, effects of atmosphere and chain scission as well as initiation of cyclization. In this work, PAN fiber as well as a PAN solution was irradiated under different atmospheres. The structure of crosslinked bonds, molecular weights and thermal reactivity were analyzed. It is discovered that gamma ray irradiation on PAN brought chains crosslinking and scission as long as cyclization. The large amount of crosslinked bonds were discovered to be –C N–N C–, while oxygen inhibited nitriles crosslinking. The crosslinking structure rather than remained radicals initiated cyclization during thermal treatment, which was broken and reproduced polyimine radicals at higher temperature.

Carbon fibers (CFs) were prepared from polyacrylonitrile fibers pre-irradiated with γ-ray irradiation in air prior to heat treatment and then by continuous stabilization and carbonization. The structural changes of fibers during heat treatment and the mechanical properties of the resultant CFs were investigated using dynamic mechanical analysis, wide-angle X-ray diffraction, small-angle X-ray scattering, and universal testing machine. It is found that not only the stabilization time was shortened with the increasing absorbed doses, but also the preferred orientation of carbon layers in the CFs was increased initially with the increasing absorbed doses and then decreased. Consequently, the tensile strength and Young’s modulus of CFs were increased by 13.2 and 2.6 % at an appropriate dose, respectively, in which skin–core structure in CFs was relieved according to SEM images. Hence, it is believed that irradiation technology-assisted stabilization has a significant potential in CF industry.

The effects of oxygen content in the atmosphere on thermal oxidative stabilization of polyacrylonitrile fibers have been studied based on the evolution of the interaction between cyclization and oxidation reactions. The results indicate that cyclization propagation was inhibited in the initial few minutes due to radical adsorption by the oxygen in the atmosphere, and then the cyclization was promoted with dehydrogenation going by oxidation, whereas the oxidation reaction was always promoted with the cyclization structure. Resultantly, a high oxygen content atmosphere didn't result in a low cyclization degree and excessive oxidation in stabilized fibers, while a low oxygen content atmosphere introduced a skin–core structure because of insufficient oxygen diffusion and rapid oxidation rate in the later stage. Finally, according to the tensile strength of carbon fibers, the optimum oxygen content in the thermal stabilization atmosphere was determined to be 15–21%.

An electric vehicle needs to use multiple individual batteries in a set to meet the requirements for use. This then imposes very strict requirement for the consistency in performance among individual batteries. This article has studied the internal resistance on the consistency in a set of batteries at low temperatures. The result indicates, the inconsistency of internal resistance among individual batteries connected in series in a set will hinder the performance of the batteries set. During the process of recharge, because of the difference in internal resistance, the recharge voltages applied to individual batteries in serial connection are different, resulting in the inconsistency in recharge voltage among batteries. And as the process of recharge goes on, the voltage of the battery with higher internal resistance may reach the upper limit on recharge voltage early. As far as the batteries in parallel connection in a set is concerned, because of the difference in internal resistance, the recharge currents distributed among individual batteries are different, with the voltages of the batteries at higher recharge currents to rise fast.

Lithium-ion batteries are widely applied for its advantages of being high in energy density, low in self-discharge rate, and high in maximal cycles, having no memory effect, and being pollutant-free. Accurately predicting the service lives of lithium-ion batteries is the important basis for reasonably working out battery replacement policy and ensuring safe use. For the purpose of this article, an acceleration model is devised for the valid period of capacity and the effect of temperature on lithium-ion batteries, revealing the pattern in the effects of capacity-related factors, and providing the fundemental data for the use of batteries at low temperatures.

As the lack of on-spot testing equipment for synchronous Phasor Measurement Unit (PMU), the on-spot testing work of PMU has not been carried out effectively. So the function of Wide area measurement system (W AMS)based on PMU was restricted greatly. In the on-spot PMU testing, the major issues are the implement of the power angle measurement and sufficient dynamic-precision. To solve these problems, we developed a high-precision PMU testing device based on the synchronous clock source in this paper. The proposed device can output amplitude, phase, frequency and low frequency vibrator of signals, which also synchronize with the second pulse of Global Positioning System (GPS). We further constructed the synchronous simulated system by the PMU testing device we developed, which is used for implementing the test on the spot. It is effective not only for static precision, but also for dynamic precision and functions of PMU.

In this paper, not only the effect of γ-ray irradiation on the chemical structures and thermal properties of PAN fibers, but also the corresponding reaction mechanisms are investigated. We report a new solubility measurement adopting sulfuric acid solution as a solvent to deeply discern cyclization and crosslinking reactions of PAN fibers after γ-ray irradiation. After the irradiation, the intramolecular cyclization of PAN fibers was dominant at relatively low doses (

The effect of a different stretching stress at different heat treatment temperatures (HTT) on the structure and the mechanical properties of polyacrylonitrile (PAN)- and rayon-based carbon fibers was studied. The tensile strength increases first and then decreases with increasing stretching stress, whereas the Young’s modulus of the fibers continuously increases. The behavior of PAN- and rayon-based carbon fibers is similar with increasing stretching stress, but the tensile strength of PAN fiber decreased while that of rayon fiber increased with increasing HTT, what is more, the latter have a considerable lower tensile strength and modulus for equivalent processing conditions. The structure of the fibers was investigated with X-ray diffraction. A continuous change toward a nanostructure with a higher order was observed, which explains the increase in the Young’s modulus. For more complex dependence of the tensile strength on the processing conditions, a quantitative model to describe the effect of stretching stress at different HTT on preferred orientation degree and shear modulus is proposed. From the critical stress fracture of carbon fiber analysis, we can understand the different changes of tensile strength of both type fibers with stretching stress at different HTT.

The influence of heat treatment temperature from 1400 to 2840 °C and time from 1.2 to 12.0 min on the structure and mechanical properties of polyacrylonitrile carbon fibers was studied. It was observed that the Young’s modulus increased with increasing temperature and time, but the tensile strength exhibited different variation trends with the different processing methods. For a fixed time of 1.2 min, the strength dropped from 4.6 GPa at 1400 °C to 2.6 GPa at 2840 °C, (~43.5 %) as opposed to a 63.9 % increase in Young’s modulus. However, when the treatment time was increased to 6.0 min at 2500 °C, the tensile strength decreased only by 1.9 %, from 3.71 to 3.64 GPa, versus a nearly 20.0 % increase in Young’s modulus. The same situation was found for treatment at 2000 and 2700 °C. Raman spectroscopy and uniform stress model analysis show that the degree of covalent cross-linking between the graphene planes decreased as temperature increased, while it remained almost constant as treatment time was increased. It is believed that during heat treatment of a carbon fiber, the cross-linking collapses at the beginning but the crystalline size keeps growing with prolonging time, so the tensile strength decreases little with further heat treatment while tensile modulus keeps increasing.

The influence of gamma-irradiation on the structure and mechanical properties of polyacrylonitrile-based carbon fibers was studied. It was observed that the Young’s modulus of the fibers irradiated increased with irradiation dose, increasing to 267 GPa at 300 kGy, a 16.1% improvement compared to that of as-received carbon fiber. However, the tensile strength increased to 5.4 GPa at 30 kGy, i.e., a 17.4% increase, and then dropped to 4.65 GPa at 300 kGy, which is almost the same as for the untreated fiber. Uniform stress model analysis and Raman spectroscopy show that the degree of covalent cross-linking between the graphene planes increased to a maximum at 30 kGy and then remained almost constant with further irradiation. The SEM images show that the degree of surface roughness increased with the increasing irradiation dose. It is believed that when the dose is less than 30 kGy, the increased cross-linking is the dominant effect, and thus improves the tensile strength. On the other hand, further irradiation generates surface flaws, which neutralizes the increase and results in a decrease of tensile strength.

Polyacrylonitrile (PAN) fibers were heated and stretched in a steam bath mixed with nitrogen in the early stage of stabilization. During this process, the flexible linear chain of PAN molecule was converted to a rigid ladder structure by intramolecular cyclization. The shrinkage tension along the fiber axis decreased during this heat treatment, because water molecules here acted as a plasticizer for stretching. Consequently, the preferred orientation of ladder molecules in the stabilized fibers was enhanced. As a result, the preferred orientation, crystallite dimensions, and mechanical properties of the resultant carbon fibers (CFs) and graphite fibers (GFs) were improved, comparing with the corresponding CFs and GFs without pretreatment in the steam bath. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.

The effects of tension on the crystalline structure and cyclization of polyacrylonitrile fibers during stabilization were investigated. The degree of cyclization was measured by Fourier transform infrared spectroscopy and differential scanning calorimetry. The crystalline structure was characterized by wide-angle X-ray diffraction. When the fibers were heat-treated at temperatures between 175 and 218°C, the tension mainly affected the cyclization in the amorphous regions through changes in the spatial distance of the chain segments; this led to a relatively higher cyclization degree under moderate tension. When the temperatures ranged from 226 to 232°C, the reactions extended to the crystalline regions. The chemical bonds became greater in the cross section of the fibers, and this was caused by cyclization structures formed in the former stage. Therefore, the optimum tension was higher than in the prior temperature range. At higher temperatures ranging from 238 to 270°C, a crosslinked structure formed, so the optimum tension increased continually. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42182.