Optimal Ascent Guidance for Air-Breathing Launch Vehicle Based on Optimal Trajectory Correction

An optimal guidance algorithm for air-breathing launch vehicle is proposed based on optimal trajectory correction. The optimal trajectory correction problem is a nonlinear optimal feedback control problem with state inequality constraints which results in a nonlinear and nondifferentiable two-point boundary value problem (TPBVP). It is difficult to solve TPBVP on-board. To reduce the on-board calculation cost, the proposed guidance algorithm corrects the reference trajectory in every guidance cycle to satisfy the optimality condition of the optimal feedback control problem. By linearizing the optimality condition, the linear TPBVP is obtained for the optimal trajectory correction. The solution of the linear TPBVP is obtained by solving linear equations through the Simpson rule. Considering the solution of the linear TPBVP as the searching direction for the correction values, the updating step size is generated by linear search. Smooth approximation is applied to the inequality constraints for the nondifferentiable Hamiltonian. The sufficient condition for the global convergence of the algorithm is given in this paper. Finally, simulation results show the effectiveness of the proposed algorithm

A re-evaluation of woods used in Chinese historic furniture

This article discusses popular Chinese historic furniture woods relatively unfamiliar to the non-Asian collections. In this discussion, woods will be called by Chinese names accompanied by Latinate or English names observing macroscopic and some microscopic features. Woods encountered in Ming and Qing hardwood furniture are discussed; Zi-tan (Sandalwood), Huang-hua-li (Yellow flowering pear), Hong-mu (Mahogany - redwood), Ji-chi mu (Chicken Wing Wood), Tie-li mu (Ironwood), Wu-mu (Northern Elm), and Hua-mu (burl). The article is presented in two parts. Part one introduces the reader to the complexities and challenges of understanding these woods, as well as presenting seven invaluable species used in Chinese fine furniture

Effects of Extrusion on Nutritional Quality and Physicochemical Properties of Multigrain Meal Replacement Powder

Using highland barley, mung bean, black bean and Tartary buckwheat as raw materials, the multigrain meal replacement powder was set by twin-screw extrudation technology. The changes of nutrient composition, volatile flavor, crystal structure and other physicochemical properties were tested before and after extrudation. The results showed that the contents of protein, fat, moisture, starch, total phenol and total flavone of multigrain meal replacement powder were reduced by 2.83%, 0.47%, 4.45%, 2.62%, 17.89 mg/100 g and 9.02 mg/100 g, respectively. The changes of dietary fiber and ash were not significant. The aldehydes, alcohol and heterocyclic substances that contribute more to the flavor were increased, which greatly improved the flavor. The crystal structure changed from A-type to V-type, and the crystallinity reduced by 24.97%. RVA and DSC results showed that the peak viscosity, minimum viscosity, disintegration value, final viscosity, recovery value and peak time decreased by 156, 46, 110, 111, 177 cP and 2.2 min, respectively. The enthalpy change decreased to 0.15 J·g−1, indicating that most of the starch had been gelatinized. The results of gel texture showed that the hardness and adhesion decreased by 35.72 g and 4.08 g respectively, while the adhesion, cohesiveness, elasticity and capability increased by 5.11 g, 0.19 Ratio, 5.08 mm and 1.98 mJ respectively, giving it a good taste. The study of the quality characteristics of the powder showed that the content of soluble solid and the water holding capacity increased while the oil holding capacity decreased. The characteristics of power were obviously improved. The color changed obviously

Research on the influence of team psychological capital on team members’ work performance

Team psychological capital is the positive psychological state of a team and has a positive impact on the human resource management and performance management of the team. Team members’ work performance, as a component of team performance, has an important impact on improving team performance. However, there is less cross-level impact analysis between the two. The purpose of this paper is to explore the mechanisms of the cross-level effects of team psychological capital on members’ performance. A paired questionnaire survey was administered to 387 human resource management team members from 86 human resource management teams across China, and SPSS 22.0, AMOS 23.0, and HLM 6.08 software were used to analyze the questionnaire data at the same level and across levels. The test shows that the cross-level positive effect of team psychological capital on team members’ work performance is established, and the cross-level mediating role of team members’ psychological capital and team support between the two is established. It enriches the cross-level research from team to individual, refines and enriches the research on the impact of team psychological capital on individual behavior, and provides new ideas for team management in companies. Therefore, when conducting team management, enterprises can enhance team members’ psychological capital by improving team psychological capital, thereby improving team members’ work performance and team efficiency

A re-evaluation of woods used in Chinese historic furniture (part two)

This second article discusses popular Chinese historic furniture woods relatively unfamiliar to the non-Asian collection. In this discussion, woods will be called by Chinese names accompanied by Latinate or English names observing macroscopic features. This second part presents eleven prize woods used in Chinese regional furniture which are observed macroscopically, eight other secondary woods as encountered in Chinese historic furniture and a list of fifteen woods occasionally found in Chinese regional furniture

improved linear analysis on block cipher multi2

Developed by Hitachi, MULTI2 is a block cipher used mainly to secure the multimedia content. It was registered in ISO/IEC 9979 and was patented in US and Japan. MULTI2 uses the Feistel structure and operates on the 64-bit blocks. The encryption key has 256 bits. This paper studies the linear analysis on MULTI2. We give a detailed bias analysis on MULTI2 round functions. For the first time formal proofs on their bias properties are given. This allows to find a new 4-round bias 2-2. Previously, the best 4-round bias 2-5.7 was proposed. Using our results on the MULTI2 round functions, we propose the linear attacks on r-round MUTLI2 to recover the encryption key. Our linear attack can recover the 256-bit encryption key in time 246, 2 60.4, 283.8, 291.7, 2123.4, 2 123.2 of r-round encryptions for r = 8, 12, 16, 20, 24, 28 respectively. Further, we can recover the 32-bit sub-key in last round much faster than the whole encryption key recovery, i.e., in time 237 for r = 8, 12, 16, 20, 24. Note that previously, the best linear key-recovery attack was a 20-round attack with time 293.4 (of 20-round encryptions) and data 239.2. As ISO register recommends to use at least 32 rounds, our attacks remain to be theoretical and do not threaten security for the practical use currently. © Springer-Verlag 2012.Developed by Hitachi, MULTI2 is a block cipher used mainly to secure the multimedia content. It was registered in ISO/IEC 9979 and was patented in US and Japan. MULTI2 uses the Feistel structure and operates on the 64-bit blocks. The encryption key has 256 bits. This paper studies the linear analysis on MULTI2. We give a detailed bias analysis on MULTI2 round functions. For the first time formal proofs on their bias properties are given. This allows to find a new 4-round bias 2-2. Previously, the best 4-round bias 2-5.7 was proposed. Using our results on the MULTI2 round functions, we propose the linear attacks on r-round MUTLI2 to recover the encryption key. Our linear attack can recover the 256-bit encryption key in time 246, 2 60.4, 283.8, 291.7, 2123.4, 2 123.2 of r-round encryptions for r = 8, 12, 16, 20, 24, 28 respectively. Further, we can recover the 32-bit sub-key in last round much faster than the whole encryption key recovery, i.e., in time 237 for r = 8, 12, 16, 20, 24. Note that previously, the best linear key-recovery attack was a 20-round attack with time 293.4 (of 20-round encryptions) and data 239.2. As ISO register recommends to use at least 32 rounds, our attacks remain to be theoretical and do not threaten security for the practical use currently. © Springer-Verlag 2012

Serving and Optimizing Machine Learning Workflows on Heterogeneous Infrastructures

With the advent of ubiquitous deployment of smart devices and the Internet of Things, data sources for machine learning inference have increasingly moved to the edge of the network. Existing machine learning inference platforms typically assume a homogeneous infrastructure and do not take into account the more complex and tiered computing infrastructure that includes edge devices, local hubs, edge datacenters, and cloud datacenters. On the other hand, recent machine learning efforts have provided viable solutions for model compression, pruning and quantization for heterogeneous environments; for a machine learning model, now we may easily find or even generate a series of models with different tradeoffs between accuracy and efficiency. We design and implement JellyBean, a framework for serving and optimizing machine learning inference workflows on heterogeneous infrastructures. Given service-level objectives (e.g., throughput, accuracy), JellyBean automatically selects the most cost-efficient models that met the accuracy target and decides how to deploy them across different tiers of infrastructures. Evaluations show that JellyBean reduces the total serving cost of visual question answering by up to 58%, and vehicle tracking from the NVIDIA AI City Challenge by up to 36% compared with state-of-the-art model selection and worker assignment solutions. JellyBean also outperforms prior ML serving systems (e.g., Spark on the cloud) up to 5x in serving costs

Effect of Particle Concentration and Pipe Materials on the Formation of Biofilms in Drinking Water Distribution Systems

Microorganism rebreeding and biofilm shedding enter the water body in the process of a drinking water distribution system (DWDS), which poses a threat to public health. Particles in water can gather pollutants as well as providing favorable growth conditions for bacteria. To date, there are a few studies which focus on the relationship between particles and biofilm formation. Therefore, the microbial diversity of biofilms in the different pipe materials and the effect on particle concentration on biofilm formation were investigated in this study. Experiments were carried out under a simulative DWDS (including iron (DI) and polyvinyl chloride (PVC) pipe). The results showed that the microbial diversity in biofilms followed this order: DI pipe > PVC pipe > DI pipe (upper). Moreover, the microbial biomass of biofilm and the fluorescence intensity of extracellular polymeric substances (EPS, produced by microorganisms) were the largest in the absence of particles. The amount of biofilm bacterial and the fluorescence intensity of EPS both showed first an increasing and then decreasing trend with particle concentration increasing. When particle concentration was relatively low, the absorption of particles and bacteria played a major role, however, with the increasing particle concentration, more stable particle–particle were formed and thus, EPS was easily extracted, resulting in the increase of fluorescence intensity of EPS

Research on the side converter system of wind power grid based on fractional LCL filter

Abstract The power electronic converters and grid‐connected filters were important components of the permanent magnet direct drive wind power generation system whose performance directly determines the quality of wind power generation. In past modeling, analysis, and control studies, capacitive and inductive components were often treated as integral‐order components. However, the inductance and capacitance components in the actual permanent magnet direct drive wind generator were fractional‐order components, and their electrical characteristics will change with the change of order, which had an important impact on the dynamic and static characteristics of the system. In this paper, the mathematical model of the fractional‐order LCL (FOLCL) filter was derived. Through simulation, it could be seen that the FOLCL filter can avoid resonance fundamentally. At the same time, the fractional‐order PI (FOPI) controller was introduced into the machine‐side current converter, and the parameters of the FOPI controller of the outer speed loop and the inner current loop were adjusted by using the time‐domain optimization method. The results showed that the efficiency of the FOPI controller was significantly better than that of the integer‐order PI controller in realizing maximum wind energy capture. It provides theoretical support and practical application value for the stable operation of the wind power generation system