Reinforced temperature control of a reactive double dividing-wall distillation column

The mass and thermal coupling makes the control of the reactive double dividing-wall distillation column(R-DDWDC) an especially challenging issue with a highly interactive nature. With reference to the separation of an ideal endothermic quaternary reversible reaction with the most unfavorable ranking of relative volatilities(A + B ■ C + D with α_(A)>α_(C)>α_(D)>α_(B)), the operation rationality of the R-DDWDC is studied in this contribution. The four-point single temperature control system leads to great steady-state discrepancies in the compositions of products C and D and the reason stems essentially from the failure in keeping strictly the stoichiometric ratio between reactants A and B. A temperature plus temperature cascade control scheme is then employed to reinforce the stoichiometric ratio control and helps to secure a substantial abatement in the steady-state discrepancies. A temperature difference plus temperature cascade control scheme is finally synthesized and leads even to better performance than the most effective double temperature difference control scheme. These outcomes reveal not only the operation feasibility of the R-DDWDC but also the general significance of the proposed temperature difference plus temperature cascade control scheme to the inferential control of any other complicated distillation columns.

Best bounds on the distance between 3-direction quartic box spline surface and its control net

We present the best bounds on the distance between 3-direction quartic box spline surface patch and its control net by means of analysis and computing for the basis functions of 3-direction quartic box spline surface.Both the local bounds and the global bounds are given by the maximum norm of the first differences or second differences or mixed differences of the control points of the surface patch.

New design of high-precision oven controlled crystal oscillator

Combining oven controlled technique,digital compensation,high-resolution frequency difference measurement and self-calibration technique,a new design method of precise oven controlled crystal oscillator（OCXO） is proposed.Fine compensation is made in the vicinity of the crystal temperature inflection point by using the non-real-time temperature compensation strategy,and self-calibration system is integrated in the crystal.The method improves the digital compensated phase noise,simplifies the traditional OCXO development system,reduces the cost and shortens the developing cycle.Experiment results show that with a standard reference signal and self-calibration updated data,the oscillator can work stable and achieve its best performence.The performance index of crystal oscillator had an improvement with one to two orders of magnitude on the basis of original technical index.The method is widely used in the improvement of high-end crystal oscillator and atomic clock.

Distribution Patterns of Remaining Hydrocarbons Controlled by Reservoir Architecture of Distributary Channel with Different Channel Style: S2 Formation of Songliao Basin, China

1 Introduction Reservoir architecture analysis of distributary channel of Daqing oilfield has drawn consistent interest among development geologists and petroleum engineers over the last decade(Lv et al.,1999;Zhou et al.,2008;Zhang et

Evaluation of a new method for quantification of heat tolerance in different wheat cultivars

Heat stress seriously affects wheat production in many regions of the world. At present, heat tolerance research remains one of the least understood fields in wheat genetics and breeding and there is a lack of effective methods to quantify heat stress and heat tolerance in different wheat cultivars. The objective of this study was to use various wheat cultivars to evaluate stress intensity(δ) and a new method for quantification of heat tolerance and compare this technique with three other currently utilized methods. This new parameter for heat tolerance quantification is referred to as the heat tolerance index(HTI) and is an indicator of both yield potential and yield stability. Heat treatments were applied in a controlled setting when anthesis had been reached for 80% of the wheat. The stress intensity evaluation indicated heat shock was the main factor associated with kernel weight reduction while grain yield reduction was mainly associated with chronic high temperature. The methods evaluation showed that a temperature difference of 5°C from natural temperatures was a suitable heat treatment to compare to the untreated controls. HTI was positively correlated with yield under heat stress(r=0.8657, δ=0.15, in 2009–2010; r=0.8418, δ=0.20, in 2010–2011; P<0.01), and negatively correlated with yield reduction rate(r=–0.8344, in 2009–2010; r=–0.7158, in 2010–2011; P<0.01). The results of this study validated the use of HTI and temperature difference control for quantifying wheat heat tolerance that included the yield potential and the stability of different wheat cultivars under heat stress. Additionally, 10 wheat cultivars showed high HTI and should be further tested for their heat confirming characteristics for use in wheat heat tolerance breeding.

A Parallel Search Genetic Algorithm Based on Multiple Peak Values and Multiple Rules

In this paper the Hamming distance is used to contr ol individual difference in the process of creating an original population, and a peak-depot is established to preserve information of different peak-points. So me new methods are also put forward to improve optimization performance of genet ic algorithm, such as point-cast method and neighborhood search strategy around peak-points. The methods are used to deal with genetic operation besides of cr ossover and mutation, in order to obtain a global optimum solution and avoid GA ’s premature convergence. By means of many control rules and a peak-depot, the new algorithm carries out optimum search surrounding several peak-points. Alon g with evolution of individuals of population, the fitness of peak-points of pe ak-depot increases continually, and a global optimum solution can be obtained. The new algorithm searches around several peak-points, which increases the prob ability to obtain the global optimum solution to the best. By using some example s to test the modified genetic algorithm, the results indicate what we have done makes the modified genetic algorithm effectively to solve both of linear optimi zation problems and nonlinear optimization problems with restrictive functions.

多弹性支撑设备的同步定相振动控制研究（英文）

This paper describes an analytical investigation into synchrophasing,a vibration control strategy on a machinery installation in which two rotational machines are attached to a beam-like raft by discrete resilient isolators.Forces and moments introduced by sources are considered,which effectively represent a practical engineering system.Adjusting the relative phase angle between the machines has been theoretically demonstrated to greatly reduce the cost function,which is defined as the sum of velocity squares of attaching points on the raft at each frequency of interest.The effect of the position of the machine is also investigated.Results show that altering the position of the secondary source may cause a slight change to the mode shape of the composite system and therefore change the optimum phase between the two machines.Although the analysis is based on a one-dimensional Euler– Bernoulli beam and each machine is considered as a rigid-body,a key principle can be derived from the results.However,the factors that can influence the synchrophasing control performance would become coupled and highly complicated.This condition has to be considered in practice.

Optimal control for spatial-temporal distributed nonlinear autoregressive with exogenous inputs correlation model of steel rolling reheating furnace: a coordinated time-sharing control approach

Accurate control of slab temperature and heating rate is an important significance to improve product performance and reduce carbon emissions for steel rolling reheating furnace(SRRF).Firstly,a spatial temporal distributed-nonlinear autoregressive with exogenous inputs correlation model(STD-NARXCM)to spatial temporal distributed-autoregressive with exogenous inputs correlation model(STD-ARXCM)in working point is established.Secondly,a new coordinated time-sharing control architecture in different time periods is proposed,which is along the length of the SRRF to improve the control performance.Thirdly,a hybrid control algorithm of expert-fuzzy is proposed to improve the dynamic of the temperature and the heating rate during time period 0 to t_(1).A hybrid control algorithm of expert-fuzzy-PID is proposed to enhance the control accuracy and the heating rate during time period t_(1) to t_(2).A hybrid control algorithm of expert-active disturbance rejection control(ADRC)is proposed to boost the anti-interference and the heating rate during time period t_(2) to t_(3).Finally,the experimental results show that the coordinated time-sharing algorithm can meet the process requirements,the maximum deviation of temperature value is 8-13.5℃.

Threshold Controlled Scheme of Difference Expansion Techniques for Reversible Watermarking

Since Tian Jun proposed the difference expansion embedding technique,based on which,many reversible watermarking techniques were proposed.However,these methods do not perform well when the payload is high.In this paper,we proposed an expandable difference threshold controlled scheme for these three methods.Experiments show that our scheme improves the performance of these three methods for heavy payload.