A similarity score-based two-phase heuristic approach to solve the dynamic cellular facility layout for manufacturing systems

The dynamic cellular facility layout problem (DCFLP) is a well-known NP-hard problem. It has been estimated that the efficient design of DCFLP reduces the manufacturing cost of products by maintaining the minimum material flow among all machines in all cells, as the material flow contributes around 10–30% of the total product cost. However, being NP hard, solving the DCFLP optimally is very difficult in reasonable time. Therefore, this article proposes a novel similarity score-based two-phase heuristic approach to solve the DCFLP optimally considering multiple products in multiple times to be manufactured in the manufacturing layout. In the first phase of the proposed heuristic, a machine–cell cluster is created based on similarity scores between machines. This is provided as an input to the second phase to minimize inter/intracell material handling costs and rearrangement costs over the entire planning period. The solution methodology of the proposed approach is demonstrated. To show the efficiency of the two-phase heuristic approach, 21 instances are generated and solved using the optimization software package LINGO. The results show that the proposed approach can optimally solve the DCFLP in reasonable time.     

芳氨基硫脲类化合物的质谱研究（Ⅰ）

本文报道了８种新的芳氨基硫脲类化合物即１－（２＇羧基苯基）－４－烷基氨基硫脲的电子轰击质谱。结果表明，该类化合物具有较强的分子离子峰Ｍ＾＋，分子离子的断裂以Ｎ－Ｎ键和Ｃ－Ｎ键的断裂为主，并伴随六员环和四员环过渡态氢重排，生成的碎片离子继续脱去水分子或其它小分子，从而产生一系列特征离子，包括骨架重排离子。４－位Ｎ上的取代烷基对谱图有一定的影响。     

双酚A生产中母液裂解和重排的研究

对双酚Ａ生产过程母液裂解重排系统,分别在第二裂解器和母液罐中加催化剂的两种不同工艺条件下,研究了温度对裂解重排反应的影响和精馏去除裂解产物中杂质的办法。试验结果表明,提高裂解温度可提高裂解回收率;在裂解气相产物冷凝前通过精馏可有效去除其中的色满等杂质;在母液罐或第二裂解器中加催化剂两种工艺下裂解重排反应无明显差别     

一种新型链状手性Schiff碱配体的合成

以苯酚和邻甲酚为起始原料,合成了一个新型链状手性Schiff碱配体(5,5-亚甲基一双-[(R,R)-{N-(3-甲基水杨醛)-N-(3’,5’-双-叔丁基-2’-羟基苯乙酮)／-1,2-二苯乙二胺]),并对其进行表征。在邻甲酚的羟基邻位甲酰化过程中,用三乙胺代替六甲基磷酰三胺(HMPA)定位,取得了较好的效果。通过对传统的Fries重排进行研究和改进,以较高的产率合成了新的中间体(3,5-二叔丁基-2-羟基苯乙酮)。     

2-嘧啶氧基-N-芳基苄胺类化合物的合成及其重排副反应

2-嘧啶氧基苄基溴与芳胺反应合成2-嘧啶氧基-N-芳基苄胺类化合物,反应过程中会发生生成2-羟基-N-芳基-N-嘧啶基苄胺副反应,即重排反应。芳胺空间位阻越小,亲核性越强,副反应越容易发生,产物除草活性越低。     

Isomerisation of 1,2-Epoxyalkanes: Effect of Different Solid Acids on Product Distribution,Mechanism and Kinetics

The rearrangement of epoxides over acidic and superacidic catalysts leads to several products with selectivity to the desired aldehyde depending upon the nature of the catalyst surface and the reaction conditions. This paper reports the studies with 1,2-epoxyoctane as a model compound, over several catalysts such as sulphated zirconia and zeolites, and dodecatungstophosphoric acid, phosphoric acid and ZnCl₂ supported on silica, clay and carbon. The typical products of rearrangement are aldehyde, allylic alcohols, furan and aldol. A mechanism for the formation of these species is given. H₃PO₄/SiO₂, dodecatungstophosphoric acid supported on K-10 clay and ZSM-5 were found to be efficient under different conditions. A kinetic model is presented. © 1997 SCI.     

Synthesis and characterization of new soluble and thermostable polyimides via novel diisocyanates

A facile synthesis of two novel diisocyanates containing methylene groups and preformed imide structure is described. Furthermore, six thermally stable and soluble polyimides were synthesized by polycondensation of these two diisocyanates with pyromellitic dianhydride (PMDA), 3, 3 ′,4, 4 ′‐benzophenonetetracarboxylic dianhydride (BTDA) and hexafluoroisopropylidene‐2,2‐bis‐(phthalic anhydride) (6FDA) in N,N ‐dimethyl acetamide. All monomers and polymers were characterized by conventional methods and their physical properties such as solution viscosity, solubility properties, thermal stability and thermal behaviour were studied. © 1999 Society of Chemical Industry     

Fluoroalcohol-mediated reductive iodonio-Claisen rearrangement: Synthesis of complex ortho-substituted-allyl iodoarenes? ?

Reductive iodonio-Claisen rearrangement (RICR) involving λ³-iodanes and allyl or substituted-allyl silanes in fluoroalcohols, such as 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and 2,2,2-trifluoroethanol (TFE), was studied for the synthesis of complex ortho-allyl or substituted-allyl iodoarenes. In comparison to the previously reported condition involving boron trifluoride diethyl etherate, the RICR mediated by fluoroalcohols was found to proceed more effectively. The resulting complex ortho-allyl iodoarenes are useful synthetic intermediates and can be readily converted to various heterocyclic compounds.     

Trifluoromethanesulfonic Acid‐Catalyzed Tandem Semi‐Pinacol Rearrangement/Alkyne‐Aldehyde Metathesis Reaction of Arylpropagylsulfonamide‐Tethered 2,3‐Epoxycyclohexan‐1‐ols to Spiropiperidines

A simple and efficient trifluoromethanesulfonic acid‐catalyzed cycloisomerization of arylpropagylsulfonamide‐tethered 2,3‐epoxycyclohexan‐1‐ols is described. The cyclization proceeds via tandem semi‐pinacol rearrangement/alkyne‐aldehyde metathesis to afford spiropiperidines under mild reaction conditions.     

焙烧温度对Silicalite-1催化环己酮肟气相Beckmann重排反应的影响

采用水热方法合成Silicalite-1分子筛,考察不同焙烧温度处理后用于催化环己酮肟气相Beckmann重排反应的催化性能。利用XRD,IR,BET和热分析方法对催化剂进行表征。结果表明,焙烧温度对环己酮肟的转化率和催化剂稳定性的影响较大,而对己内酰胺的选择性影响不明显。随着焙烧温度的升高,分子筛的比表面积变化不明显,而外表面积先增大后减小,微孔体积积占总孔体积积的比例呈下降趋势。最佳的焙烧温度为400 °C,在该焙烧温度下的分子筛用于气相Beckmann重排反应中的活性和稳定性最佳。