甘蔗糖厂静压饱和浸渗提汁实验研究

提出了一种适用于甘蔗糖厂的静压饱和浸渗提汁工艺,通过一定压力作用于蔗渣,采用回流饱和浸渗工艺,达到提汁的目的.实验结果表明:采用新工艺后可使蔗渣的水分、锤度、转光度比传统压榨降低6.6%、9.7%、5.8%,抽出率提高0.4%,可为甘蔗提汁领域提供新途径.     

An effective control solution for doubly-fed induction generator under harsh balanced and unbalanced voltage sags

This paper presents a novel control algorithm for the rotor-side converter of Doubly-Fed Induction Generators. The main goal is to endow the system with effective Low Voltage Ride Through capability, under harsh balanced and unbalanced grid voltage sags, without relying on dedicated auxiliary hardware, which is commonly adopted to sustain severe line faults. In this respect, nonlinear control theory arguments are applied to design a controller capable of mitigating oscillations (particularly on rotor currents and voltages) arising during line faults, therefore preventing the system from disconnecting for protection. The proposed solution adopts both feedforward and feedback terms. The former stems from a thoughtful analysis of the system internal dynamics, taking into account the effects of line voltage perturbations, which is exploited to design feasible state trajectories for the generator electromagnetic variables. Specifically, such references do not contain poorly-damped oscillatory modes of the machine natural dynamics, expressed in synchronously rotating frames (such components turn into slowly varying DC ones in a stationary frames). Then, a state feedback unit is designed according to modern saturated control techniques, accounting for constraints on rotor voltage, and steering real variables toward references, where priority given to rotor currents, to avoid rotor-side converter tripping due to overcurrent. In addition, a non standard line voltage reconstruction and dip detection scheme, based on adaptive state observers, is designed, to reliably cope with challenging faulty conditions. Detailed numerical simulations validate the proposed method benefits under severe symmetric and asymmetric dip scenarios.     

消除挤土影响的一项有效技术-消压孔

本文为解决预制桩沉桩特别是采用大吨位压桩机施工时对饱和粘性土、淤泥等所引起的严重挤土影响。现场采用一种称为＂消压孔＂的技术,从而有效地阻断了消压孔边界以外土体的挤压,同时也降低了界内土体因沉桩施工而引起的一些不良后果。通过若干工程实践,说明行之有效。     

Non-Darcy flow seepage characteristics of saturated broken rocks under compression with lateral constraint

sing an MTS816.03 test system and self-designed seepage apparatus,seepage tests of saturated broken rocks were conducted,and the influence of lithology,axial stress,grain size distribution and loading rate on seepage characteristics was analyzed.The results show that:(1) Under the same axial stress(12 MPa)the permeability of different lithologic samples increases in the order:gangue mudstone sand stone limestone.The permeability of gangue is 3 magnitudes lower than that of limestone.The absolute value of the non-Darcy coefficient β increases in the order:limestone sandstone mudstone gangue The non-Darcy coefficient β of limestone,which is positive,is 5 magnitudes lower than that of gangue.(2)With increasing axial stress,the permeability of saturated broken sandstone decreases,and the absolute value of the non-Darcy coefficient β increases.After the axial stress exceeds 12 MPa,the curves of perme ability and non-Darcy coefficient β all tend to be stable.(3) With increasing Talbol power exponent,the permeability increases,and the absolute value of the non-Darcy coefficient β decreases.(4) With increas ing loading,the permeability increases,and the absolute value of the non-Darcy coefficient β decreases When the loading rate is 0.5 kN/s,the non-Darcy coefficient β is positive.     

Impact of oil used by the frying industry on population fat intake

Chronic multifactorial diet related diseases are the major causes of death and illness worldwide. The amount and composition of fat in the diet is an important determinant of the pathobiology of many of these conditions. In the current review the associations between dietary fat and disease risk will be considered. Mean population fat intakes will be compared with dietary recommendations aimed at reducing the population burden of disease and the main sources of fat in the adult and childhood diet will be given. An assessment will be made of the principal vegetable oil sources used in the manufacture of processed foods, in particular fried foods, with particular reference to the rheological and nutritional justification for their use. The impact of the more widespread use of alternative oil sources with improved fatty acid profiles, on the fat composition of fried foods and the overall diet will be presented, demonstrating that such apparently focussed approaches could potentially result in a significant impact on population fat intake and potentially overall chronic disease burden.     

抗高温高密度饱和盐水聚磺钻井液的高温稳定性

针对高密度饱和盐水磺化钻井液抗高温稳定性差这一问题,通过对其机理进行分析,优选出了抗盐抗高温稳定剂A,并在此基础上进行改进,得到了抗盐抗高温稳定剂B。研究结果表明,在三高磺化钻井液中加入改进后的抗盐抗高温稳定剂B后,钻井液的终切力降低幅度超过50%;经170℃老化5 d后,钻井液的流变性、高温高压滤失量变化较小,克服了高密度磺化钻井液高温稳定性差、高温高压滤失量难以控制、维护处理等问题。     

声场影响过饱和糖液稳定性的机理研究

将６０℃下的过饱和糖液迅速冷却至４０℃，并附加一个声场，过饱和糖液的稳定悸降低。声波频率高的诱导期长于声波上氏的诱导期；声波功率增大，诱导期缩短。为了提示声场降低过饱和糖液稳定性的机理，测量了声场对糖液密度，折射率、电导率及粘度的影响。通过本研究，为创造一种造外力场强化工业结晶过程新的单元操作提供理论依据。     

Effects of heterogeneity distribution on hillslope stability during rainfalls

The objective of this study was to investigate the spatial relationship between the most likely distribution of saturated hydraulic conductivity(Ks) and the observed pressure head(P) distribution within a hillslope. The cross-correlation analysis method was used to investigate the effects of the variance of ln Ks, spatial structure anisotropy of ln Ks, and vertical infiltration flux(q) on P at some selected locations within the hillslope. The cross-correlation analysis shows that, in the unsaturated region with a uniform flux boundary, the dominant correlation between P and Ksis negative and mainly occurs around the observation location of P. A relatively high P value is located in a relatively low Kszone, while a relatively low P value is located in a relatively high Kszone. Generally speaking, P is positively correlated with q/Ksat the same location in the unsaturated region. In the saturated region, the spatial distribution of Kscan significantly affect the position and shape of the phreatic surface. We therefore conclude that heterogeneity can cause some parts of the hillslope to be sensitive to external hydraulic stimuli(e.g., rainfall and reservoir level change), and other parts of the hillslope to be insensitive. This is crucial to explaining why slopes with similar geometries would show different responses to the same hydraulic stimuli, which is significant to hillslope stability analysis.