Effect of microwave heating time on the gel properties of chicken myofibrillar proteins and their formation mechanism

The present work was conducted to illustrate the mechanism of gel formation of myofibrillar proteins (MPs) under different microwave heating times. The results showed that the denaturation enthalpy (ΔH) of the MPs significantly decreased when the heating time increased from 3 to 9 s and then completely disappeared as the heating time progressed, indicating that the MPs gradually denatured and subsequently aggregated with increasing heating time, which was further verified by the changes in the secondary structure, electrophoretic bands, and gel properties (e.g., water holding capacity and textural profiles) of the MPs. Microstructural images indicated that the MP gel formed under 12 s had the most compact network, indicating that extended microwave heating time could induce quality deterioration of MP gels. Moreover, the hydrophobic forces, electrostatic forces, and disulphide bonds of the MPs gradually intensified with increasing microwave heating time, suggesting that both non-covalent and covalent bonds could promote molecular denaturation and subsequent aggregation of MPs. In addition, correlation analysis revealed that the changes in the molecular conformation of MPs induced by different microwave heating times could effectively regulate the formation of MP gels and their related properties.     

A Highly Sensitive,Reversible, and Bidirectional Humidity Actuator by Calcium Carbonate Ionic Oligomers Incorporated Poly(Vinylidene Fluoride)

Sensitivity and multi-directional motivation are major two factors for developing optimized humidity-response materials, which are promising for sensing, energy production, etc. Organic functional groups are commonly used as the water sensitive units through hydrogen bond interactions with water molecules in actuators. The multi-coordination ability of inorganic ions implies that the inorganic ionic compounds are potentially superior water sensitive units. However, the particle forms of inorganic ionic compounds produced by classical nucleation limit the number of exposed ions to interact with water. Recent progress on the inorganic ionic oligomers has broken through the limitation of classical nucleation, and realized the molecular-scaled incorporation of inorganic ionic compounds into an organic matrix. Here, the incorporation of hydrophilic calcium carbonate ionic oligomers into hydrophobic poly(vinylidene fluoride) (PVDF) is demonstrated. The ultra-small calcium carbonate oligomers within a PVDF film endow it with an ultra-sensitive, reversible, and bidirectional response. The motivation ability is superior to other bidirectional humidity-actuators at present, which realizes self-motivation on an ice surface, converting the chemical potential energy of the humidity gradient from ice to kinetic energy.     

脉冲高度权重技术测量197Au中子俘获截面

脉冲高度权重技术是利用C_6D_6探测器测量中子俘获截面的一种数据处理方法。在中国散裂中子源(China Spallation Neutron Source,CSNS)的反角白光中子源(Back-n)靶站上,通过测量金靶(~(197)Au)的中子俘获截面,验证了该方法的可靠性。首先利用Geant4蒙特卡罗程序模拟给出了不同靶条件下的探测器效率,脉冲高度权重函数等基本项,使得加权后的探测器效率与γ能量成正比。然后通过实验测量了~(197)Au中子俘获截面。结果表明:测量获得的中子俘获截面数据和ENDF/B-VⅢ.0评价数据相符合,同时发现随着实验靶尺寸的不同和质子束功率的增加,会使得实验本底的扣除误差越来越大。     

EPMDA: an efficient privacy-preserving multi-dimensional data aggregation scheme for edge computing-based IoT system

In order to perform multi-dimensional data aggregation operations efficiently in edge computing-based Internet of things (IoT) systems, a new efficient privacy-preserving multi-dimensional data aggregation (EPMDA) scheme is proposed in this paper. EPMDA scheme is characterized by employing the homomorphic Paillier encryption and SM9 signature algorithm. To improve the computation efficiency of the Paillier encryption operation, EPMDA scheme generates a pre-computed modular exponentiation table of each dimensional data,and the Paillier encryption operation can be implemented by using only several modular multiplications. For the multi-dimensional data, the scheme concatenates zeros between two adjacent dimensional data to avoid data overflow in the sum operation of ciphertexts. To enhance security, EPMDA scheme sets random number at the high address of the exponent. Moreover, the scheme utilizes SM9 signature scheme to guarantee device authentication and data integrity. The performance evaluation and comparison show that EPMDA scheme is more efficient than the existing multi-dimensional data aggregation schemes.     

基于射流冲击作用的舰机适配性数值分析与优化

准确分析和控制射流冲击对航母甲板环境的影响是新型喷气偏流板设计和布局的关键所在。为了确定射流冲击影响最小的偏流板布局，运用有限体积法，采用分区混合网格方案，结合雷诺时均纳维斯托克斯（RANS）方程和SST k-ω湍流模型对喷气偏流板在不同布局下的射流冲击效应进行三维数值模拟。选取舰载机双发动机全加力状态时喷气偏流板与发动机距离不同、喷气偏流板倾角不同共12种布局组合进行射流冲击效应的对比计算,计算结果显示了喷气偏流板各布局下的流场参数、传热特性、尾喷口温升、冲击力和力矩等分布规律。定性和定量分析了燃气射流冲击下温度场和速度场的危险区域，结果表明，偏流板与发动机距离5 m、偏流板倾角45°时的布局更有利于将燃气射流向上引导。在此基础上，基于倾角最小化原则及二次导流原理优化设计了一种导流隔热性能好、工作稳定性高的被动隔热式喷气偏流板装置。     

基于步冷试验的2.25Cr-1Mo-0.25V钢母材及焊缝回火脆化研究

对原始态、步冷态、脱脆态和脱脆步冷态2.25Cr-1Mo-0.25V钢母材及焊缝冲击试验结果进行分析,得到了母材和焊缝在不同状态下的韧脆转变温度vTr54.2和FATT以及脆化度ΔvTr54.2和ΔFATT。试验结果表明,步冷试验之后,母材发生较低程度脆化或脱脆现象,但是脆化度或脱脆度较低,表明母材具有良好的抗回火脆化性能;经脱脆试验后,母材和焊缝都发生较高程度的脱脆,表明材料的脆化主要是由于回火脆化引起的,脱脆试验使得材料的韧脆转变温度降低;脱脆步冷试验后,焊缝发生较高程度的脆化,焊缝对脱脆步冷试验的敏感性较高,脱脆步冷试验有效促进了焊缝的脆化。在相同脆化条件下,母材的脆化敏感性低于焊缝,焊缝更易发生脆化。     

基于振动实测的非均质地层钻头失效分析与对策

四川盆地作为国内页岩气开发的重点区域,通过近几年的不断攻关和实践,机械钻速得到了提高,但由于受地层复杂、可钻性差、非均质性强等地质因素的影响,导致井下钻柱系统不良振动剧烈,容易出现钻头损坏严重、钻速较低等问题,严重影响了钻井时效。为了解决上述难题,以该盆地涪陵工区上二叠统龙潭组—中二叠统茅口组为例,采用井下振动高频测量工具的实测手段,测量了钻头—钻柱系统的动态振动加速度参数,结合地层的岩性和矿物组分分析,研究钻头失效原因与对策,并开展了现场试验。研究结果表明:①在非均质地层中钻进的钻头—钻柱系统产生了大于40 m/s~2的高幅值瞬时冲击振动,高幅值的瞬时冲击是导致钻头先期失效的主要原因;②提出了抑制高幅值的瞬时冲击振动采用"减振+增压"工具组合和避免井下工具共振的钻井参数;③采用钻井新参数的试验井比邻井的高幅值瞬时振动降低了17%,单只钻头进尺增加24%,钻头工作环境得到了较大的改善,钻头使用数量减少。结论认为,该研究成果能够有效地改善钻头—钻柱系统的振动状态,有利于达成延长钻头使用寿命的目标。     

Tensor Q-rank: new data dependent definition of tensor rank

Machine Learning - Recently, the $${ Tensor}~{ Nuclear}~{ Norm}~{ (TNN)}$$ regularization based on t-SVD has been widely used in various low tubal-rank tensor recovery tasks. However, these models...     

加油站电气设备引发着火爆炸事故原因分析及对策

通过对加油站电气设备引发着火爆炸事故的作业环节、发生部位、点火源和对事故原因的综合定性定量分析。指出电气设备不防爆和电气线路安装不符合防爆要求，以及规章制度不健全，管理不到位是引发着火爆炸的主要原因，提出了要提高思想认识，做好加油站防爆电气设备的全面普查摸底。要搞好新建加油站或改建项目的竣工验收和落实责任，加强防爆电气的使用管理等措施。