An augmented beam search-based algorithm for the circular open dimension problem

In this paper, we discuss the circular open dimension problem (CODP); that is a problem of the cutting/packing family. In CODP, we are given an initial strip of fixed width W and unlimited length, as well as a finite set N of n circular pieces C_i of known radius r_i,i ∈ N. The objective is to search for a global optimum corresponding to the minimum length of the initial strip containing the n pieces. We propose an augmented algorithm for solving the CODP which combines a beam search, a binary search and the well-known multi-start strategy. In addition, in order to increase the efficiency of the algorithm, we incorporate a strategy based on the separate beams instead of the pooled ones. The performance of the proposed algorithm is evaluated on a set of benchmark instances composed of a group taken from the literature and another group of randomly generated instances. The results show that the proposed algorithm is able to improve several best known solutions of the literature and it remains competitive for the new generated ones.     

A new and applicable method to calculate mass and heat transfer coefficients and efficiency of industrial distillation columns containing structured packings

Most of the methods developed for efficiency estimation of distillation columns were based on the empirical mass transfer and hydraulic relations correlated to laboratory data. Therefore, these methods cannot estimate efficiency of industrial columns with sufficient accuracy. In this paper, a new and applicable method was developed for calculation of efficiency (and mass and heat transfer coefficients) of distillation columns containing structured packings. This method has potential advantages; e.g., it can calculate efficiency without using any empirical mass transfer and hydraulic correlations and models, and without the need to estimate the operational and hydraulic parameters of column. Therefore, it will be free of errors, limitations, and complexities of such empirical items. In addition, precision of the method does not decrease with increasing complexity of operating conditions and design parameters of column. The method can be used for efficiency calculation of any structured packing, including new ones, in distillation columns.     

The effects of rosemary extract combination with vacuum packing on the quality changes of Atlantic mackerel fish burgers

The effects of the use of antioxidant technology on the quality of mackerel burgers stored at 4 °C were investigated in terms of sensory, biochemical [thiobarbituric acid (TBA), total volatile basic nitrogen (TVB‐N), peroxide value (PV) and free fatty acids (FFA)] and microbiological analyses [total viable count (TVC)]. Fish meat was divided into three groups; the control (C) without rosemary extract, the second group with 0.4% rosemary extracts (Group A) and the third with 0.8% rosemary extracts (Group B). Results showed that the TVB‐N level did not exceed acceptability limit (30–35 mg 100 g^?1) for all groups. TBA value for the control significantly increased from 1.47 to 4.80 MA kg^?1 whereas it slightly increased in treatment groups as the storage time increased. Significantly higher PV and FFA (P < 0.05) were obtained from the control group. Rosemary extract, in combination with vacuum pack was effective in controlling the growth of bacteria and biochemical indices.     

浮头换热器填料函的优化设计

根据实例介绍了对某可抽式浮头换热器填料函的改进方法,并进行结构优化设计,达到了方便维护检修,延长检修周期,大大降低成本的目的。     

30万t/a离子膜烧碱液氯工序运行总结

介绍了常温高压法液氯生产工艺,总结了运行中出现的问题并提出了改进办法。     

A Discussion of the Compound Sand Control Technique of High Pressure Packing and Moderate Acidification

Acidification can both eliminate formation damage and improve flow passage, which can be good for improving single well productivity. Based on this, the authors bring up the thought of moderate acidification technique for sandstone reservoir, and combine it with high pressure packing technique, and one step further, presents a compound sand control technique of high pressure packing and moderate acidification. At the same time, the authors preliminarily discuss the main points of this technique and analyze its mechanism of sand control and yield increase as well as its adaptability. The main purpose of this technique is to clean out the clay and mud in the immediate vicinity of wellbore, decrease the fine content or the particle size in that area, enlarge the seepage channel, and fill in optimized gravel, so as to make it conducive for transpiring the fine sand in the formation and keeping the gravel layer unblocked, as a result making the sand control life prolonged and single-well productivity raised. The keys of this compound technique are moderate acidification and gravel size optimization.     

Performance characteristics of a new spherical metal mesh packing

Various tests and analysis on hydrodynamics and mass transfer properties show that, the newly invented spherical metal mesh packing (SMMP) has excellent properties from three aspects: (i) high void space (∼99%) and lower material cost; (ii) high mass transfer efficiency; (iii) easy installation, good liquid distribution, and prevention of wall flow. Moreover, SMMP is a type of isotropic spherical unit with numerous hollow holes, which realizes the regularization of random packing. The results indicate the potential of developing high-efficiency and energy-saving SMMP-based equipment.     

C–H···O hydrogen bonding in crystals

An overview is given on C–H···O hydrogen bonding in the solid state. Following a short survey of the early literature, the general properties of C–H···O bonding are discussed. The structural characteristics and some physical consequences of C–H···O bonds are described. A number of special systems are discussed in greater detail; these include water acceptors, inclusion complexes, and some biological structures.     

Planar packing of trees and spider trees

In [A. García, C. Hernando, F. Hurtado, M. Noy, J. Tejel, Packing trees into planar graphs, J. Graph Theory (2002) 172-181] García et al. conjectured that for every two non-star trees there exists a planar graph containing them as edge-disjoint subgraphs. In this paper we prove the conjecture in the case in which one of the trees is a spider tree.