Synthesis of Polyol Tetrabromophthalate and Its Use as a Component for Preparing Foamed Polyurethanes of Reduced Flammability

A procedure was suggested for preparing brominated polyols of reduced viscosity for the synthesis of foamed polyurethanes of reduced flammability. The flame-retarding action of the synthesized polyol tetrabromophthalate in polyurethane was studied in comparison with that of other widely used flame retardants. Evaluation of the effect exerted on the flammability of the polurethane compound by the polyol tetrabromophthalate synthesized, melamine, and aluminum hydroxide shows that all the samples containing flame retardants are self-extinguishing. The shortest combustion time was observed for the sample containing 6% polyol tetrabromophthalate synthesized. The sample containing as a flame retardant additive solely the synthesized polyole tetrabromophthalate also exhibits the highest performance as a heat-insulating material from the viewpoint of thermal conductivity.

     

Determining co-combustion characteristics,kinetics and synergy behaviors of raw and torrefied forms of two distinct types of biomass and their blends with lignite

Journal of Thermal Analysis and Calorimetry - In this study, the combustion characteristics and kinetics of various mixtures of both raw and torrefied rose pulp and red pine sawdust with each other...     

Hierarchical motion planning at the acceleration level based on task priority matrix for space robot

Nonlinear Dynamics - A capacitive micromachined ultrasonic transducer (CMUT) due to many benefits is being considered as an imaging and therapeutic technology recently. The critical challenge is to...     

Band-Gap Determination from Photoconductivity Excitation Spectra

Journal of Applied Spectroscopy - The possibility to determine the direct and indirect band gap from the photoconductivity spectrum is shown. The band gap determined from the photoconductivity...     

Depth estimation of protoporphyrin IX objects in turbid media considering the fluorescence intensity ratio between two wavelengths of light for application in invasion diagnosis of gastric cancer

Optical Review - This paper demonstrates a method to estimate the depth of a fluorescence object in turbid media using dual-wavelength excited photodynamic diagnosis, to aid in the invasion depth...     

Strengthened Wiegold Conjecture in the Theory of Nilpotent Lie Algebras

Mathematical Notes - In the present paper, we strengthen the assertion of the Wiegold conjecture for nilpotent Lie algebras over an infinite field by proving that if there exists a subset of a...     

改进型单晶炉提拉系统偏心平衡研究

随着光伏行业的快速发展, 对硅单晶的品质和长晶装备的稳定性的要求也不断提高。直拉法是生产硅单晶的主要方法,通过提高单晶炉副室的高度以扩大单晶硅的生产规模。由于副室高度的大幅增加,且单晶炉提拉头质心相对于旋转轴心有一定距离,对单晶炉整体稳定性有较大影响,从而降低了单晶硅的生产质量。针对此问题,对单晶炉建立可靠的力学分析模型,采用数值仿真方法,对单晶炉整体进行动力学响应分析,计算得到副室高度增加后的单晶炉工作时中钨丝绳下端晶棒的运动规律以及最大摆动幅度,为改进设计提供依据。数值仿真分析表明提高单晶炉副室高度后,提拉头较大的质心偏心是单晶炉提拉系统发生摆动的主要原因。在此基础上提出在提拉头上添加质心调节装置,通过控制系统调节可保证提拉头质心位置在旋转轴线上以降低提拉系统的摆动。     

A Structural Entropy Measurement Principle of Propositional Formulas in Conjunctive Normal Form

The satisfiability (SAT) problem is a core problem in computer science. Existing studies have shown that most industrial SAT instances can be effectively solved by modern SAT solvers while random SAT instances cannot. It is believed that the structural characteristics of different SAT formula classes are the reasons behind this difference. In this paper, we study the structural properties of propositional formulas in conjunctive normal form (CNF) by the principle of structural entropy of formulas. First, we used structural entropy to measure the complex structure of a formula and found that the difficulty solving the formula is related to the structural entropy of the formula. The smaller the compressing information of a formula, the more difficult it is to solve the formula. Secondly, we proposed a λ-approximation strategy to approximate the structural entropy of large formulas. The experimental results showed that the proposed strategy can effectively approximate the structural entropy of the original formula and that the approximation ratio is more than 92%. Finally, we analyzed the structural properties of a formula in the solution process and found that a local search solver tends to select variables in different communities to perform the next round of searches during a search and that the structural entropy of a variable affects the probability of the variable being flipped. By using these conclusions, we also proposed an initial candidate solution generation strategy for a local search for SAT, and the experimental results showed that this strategy effectively improves the performance of the solvers CCAsat and Sparrow2011 when incorporated into these two solvers.     

A three-component cyclocondensation reaction for the synthesis of new triazolo[1,5-a]pyrimidine scaffolds using 3-aminotriazole,aldehydes and ketene N,S-acetal

Molecular Diversity - This study describes the use of 3-aminotriazole, different aldehydes and N-methyl-1-(methylthio)-2-nitroethenamine as a ketene N,S-acetal in a three-component condensation for...     

Self-Similarity in the Problem of Laminar Film Boiling on a Vertical Surface Submerged in a Large Volume of a Liquid

Technical Physics - Using the methods of self-similarity for a laminar free-convective film boiling on a vertical finite-length surface submerged into a large volume of an arbitrarily subcooled...