Experimental investigation of high temperature thermal-vibration characteristics for composite wing structure of hypersonic flight vehicles

A thermal-vibration test system is established by combining the high-temperature transient heating simulation system and vibration test apparatus, and this system can carry out experimental research on the thermal modal of high-temperature-resistant composite wing structure of hypersonic flight vehicles under high temperature environment with 1100°C. The vibration signals of the composite wing structure in high-temperature environments are transmitted to non-high temperature field by using self-developed extension configurations and then the vibration signals are measured and identified by using ordinary acceleration sensors. Based on a time-frequency joint analysis technique, the experimental data is analyzed and processed to obtain the key vibration characteristic parameters of composite wing structure, such as the natural frequency and mode shapes, in a thermal-vibration coupled environment up to 1100°C. The experimental results provide an important basis for the dynamic performance analysis and safety design of composite wing structure under high-temperature thermal-vibration conditions

Experimental investigation of high temperature thermal-vibration characteristics for composite wing structure of hypersonic flight vehicles

A thermal-vibration test system is established by combining the high-temperature transient heating simulation system and vibration test apparatus, and this system can carry out experimental research on the thermal modal of high-temperature-resistant composite wing structure of hypersonic flight vehicles under high temperature environment with 1100°C. The vibration signals of the composite wing structure in high-temperature environments are transmitted to non-high temperature field by using self-developed extension configurations and then the vibration signals are measured and identified by using ordinary acceleration sensors. Based on a time-frequency joint analysis technique, the experimental data is analyzed and processed to obtain the key vibration characteristic parameters of composite wing structure, such as the natural frequency and mode shapes, in a thermal-vibration coupled environment up to 1100°C. The experimental results provide an important basis for the dynamic performance analysis and safety design of composite wing structure under high-temperature thermal-vibration conditions

A Novel High-performance Implementation of CRYSTALS-Kyber with AI Accelerator

Public-key cryptography, including conventional cryptosystems and post-quantum cryptography, involves computation-intensive workloads. With noticing the extraordinary computing power of AI accelerators, in this paper, we further explore the feasibility to introduce AI accelerators into high-performance cryptographic computing. Since AI accelerators are dedicated to machine learning or neural networks, the biggest challenge is how to transform cryptographic workloads into their operations, while ensuring the correctness of the results and bringing convincing performance gains. After investigating and analysing the workload of NVIDIA AI accelerator, Tensor Core, we choose to utilize it to accelerate the polynomial multiplication, usually the most time-consuming part in lattice-based cryptography. We take measures to accommodate the matrix-multiply-and-add mode of Tensor Core and make a trade-off between precision and performance, to leverage it as a high-performance NTT box performing NTT/INTT through CUDA C++ WMMA APIs. Meanwhile, we take CRYSTALS-Kyber, the candidate to be standardized by NIST, as a case study on RTX 3080 with the Ampere Tensor Core. The empirical results show that the customized NTT of polynomial vector ($n=256,k=4$) with our NTT box obtains a speedup around 6.47x that of the state-of-the-art implementation on the same GPU platform. Compared with the AVX2 implementation submitted to NIST, our Kyber-1024 can achieve a speedup of 26x, 36x, and 35x for each phase

Waterways to Greenways: A Case Study in Shangjie, Zhengzhou, Henan, China

This case study introduces how we used a water sensitive approach to plan a storm water and sponge city project, which expanded into a holistic green infrastructure project. The project is in the Shangjie district in city of Zhengzhou, Henan China. The whole site is 61.16 km² including several waterways. The city is expanding into areas that were previously agricultural. Developers and city both desire to improve the ecological value of the city to boost the economic growth of the Shangjie district. The main goal for the client is to transform the existing industrial city into a more resilient and livable ecological region. Our approach is to holistically solve the region\u27s increasing demand for flood control and storm water management, and to improve ecological and recreational values along these riparian corridors. We propose additional waterways and water bodies to act as green infrastructure, then link the greenways to existing or proposed parks to form a comprehensive greenway network. Our multidisciplinary team conducted detailed investigations and collaborated extensively. The team consists of hydraulic engineers, civil engineers, environmental planners, landscape planners, urban planners, economic planners, and others. We used a variety of technologies, including GIS, Infoworks, remote sensing technology, MIKE model, and lab tests

Guest Molecules with Amino and Sulfhydryl Groups Enhance Photoluminescence by Reducing the Intermolecular Ligand-to-Metal Charge Transfer Process of Metal–Organic Frameworks

Micron-sized metal–organic framework (MOF) sheets were prepared using organic molecules with aggregation-induced emission (AIE) properties as ligands. The intermolecular ligand-to-metal charge transfer (LMCT) process occurs in MOF structures, resulting in the disappearance of the matrix coordination-induced emission (MCIE) effect and emergence of the aggregation-caused quenching (ACQ) effect. Here, we demonstrate that molecules with electron donors can compete with the LMCT process in MOF structures, thereby changing the transfer path of the excitation energy and returning it to the ground state, mainly in the form of fluorescence. Organic molecules with amino or sulfhydryl groups can act as effective electron donors, reducing the LMCT process and causing the MCIE effect of the MOF sheet. The coexistence of amino and sulfhydryl groups will strongly inhibit the LMCT process of the MOF sheet, thereby greatly enhancing the MCIE effect. Therefore, these types of molecules can be used to regulate the photoluminescence intensity of AIE-based MOF materials. In addition, there are some organic molecules with multiple carboxyl or hydroxyl groups which can produce similar effects. Finally, it was confirmed that the intermolecular LMCT process is highly sensitive, and the MOF sheet showed distinguishable fluorescence results even with the addition of small molecules in the amount of 10−9 M. Thus, it is a feasible idea to use the fluorescence changes induced by the LMCT process as a sensitive sensing method for small molecules

Experimental Investigation of the Impact of Coal Fines Migration on Coal Core Water Flooding

Coalbed Methane (CBM) has become an important gas resource in recent decades. The brittle property of coal matrix and overactive operation make the migration of coal fines inevitable. Blockage by coal fines that plugs flow paths is a non-negligible issue that results in a significant decline in gas production. By setting different experimental conditions with the following factors-coal fines concentration of the mixture displacing fluids, constant flow pump rate, inlet pressure, outlet pressure and confining pressure-six experimental schemes were designed to investigate the two-phase water and coal fines flow in natural core samples. When the differential pressure and flooding flow reach a pseudo-steady status, the equivalent permeability of coal samples can be approximately calculated considering coal fines migration. Furthermore, the influences of coal fines migration on the cleat opening and permeability variation are analyzed in the porous coal medium. The study will benefit CBM development and save pump maintenance costs. In this work, we found that maintaining the differential pressure for a longer period may result in new cleat openings and severe coal rock damage during the single-phase water flooding process. While coal fines may plug some natural cleats and pores, especially in the core samples with micro-cleats during the two-phase flooding stage, coal fines migration significantly reduces the equivalent permeability and dewatering ability of the coal rock in the earlier flooding. While enlarging the differential pressure in two-phase water and fines flooding, breakthrough of coal fines from the samples contributes to widened cleats. While coal fines are difficult to flood into the core pores for low-permeability core samples, coal fines gather in the inlet, and it is also difficult to reach the pseudo-steady status even under higher differential pressure. The damage to permeability mainly occurs in the early stage of coal fines migration, and an abrupt increase in the flow velocity can damage reservoirs and induce substantial coal fines generation. Thus, maintaining a stable effective strength and a controlled depressurization rate during drainage can effectively constrain coal fines output and decrease permeability damage within coal reservoirs

offline rfid grouping proofs with trusted timestamps

With the wide deployment of RFID applications, RFID security issues are drawing more and more attention. The RFID grouping proof aims to provide a verifiable evidence that two or more RFID tags were scanned simultaneously. It extends the yoking proof for two RFID tags, to prove the coexistence of a set of tags (e.g., some drugs can only be sold in the existence of a prescription). In many grouping proof scenarios, the time when the grouping proof was generated is critical to judge whether a transaction is legal or not, and the protocol usually should work in offline mode. Although lots of grouping proof protocols with various features have been proposed, they either work in online mode or have difficulties in generating a grouping proof with the precise transaction time in offline mode. Therefore, we propose a protocol to generate offline RFID grouping proofs with trusted timestamps, where the verifier can obtain the precise transaction time. As far as we know, it is the first practical offline grouping proof protocol that includes the precise transaction time. Properties, performance evaluation and security analysis of our design are also presented in this paper. © 2012 IEEE.University of Bradford; IEEE Technical Committee on Scalable Computing (TCSC); IEEE; IEEE Computer SocietyWith the wide deployment of RFID applications, RFID security issues are drawing more and more attention. The RFID grouping proof aims to provide a verifiable evidence that two or more RFID tags were scanned simultaneously. It extends the yoking proof for two RFID tags, to prove the coexistence of a set of tags (e.g., some drugs can only be sold in the existence of a prescription). In many grouping proof scenarios, the time when the grouping proof was generated is critical to judge whether a transaction is legal or not, and the protocol usually should work in offline mode. Although lots of grouping proof protocols with various features have been proposed, they either work in online mode or have difficulties in generating a grouping proof with the precise transaction time in offline mode. Therefore, we propose a protocol to generate offline RFID grouping proofs with trusted timestamps, where the verifier can obtain the precise transaction time. As far as we know, it is the first practical offline grouping proof protocol that includes the precise transaction time. Properties, performance evaluation and security analysis of our design are also presented in this paper. © 2012 IEEE

Optimal Economic Operation of Islanded Microgrid by Using a Modified PSO Algorithm

An optimal economic operation method is presented to attain a joint-optimization of cost reduction and operation strategy for islanded microgrid, which includes renewable energy source, the diesel generator, and battery storage system. The optimization objective is to minimize the overall generating cost involving depreciation cost, operation cost, emission cost, and economic subsidy available for renewable energy source, while satisfying various equality and inequality constraints. A novel dynamic optimization process is proposed based on two different operation control modes where diesel generator or battery storage acts as the master unit to maintain the system frequency and voltage stability, and a modified particle swarm optimization algorithm is applied to get faster solution to the practical economic operation problem of islanded microgrid. With the example system of an actual islanded microgrid in Dongao Island, China, the proposed models, dynamic optimization strategy, and solution algorithm are verified and the influences of different operation strategies and optimization algorithms on the economic operation are discussed. The results achieved demonstrate the effectiveness and feasibility of the proposed method