一种基于预稳定区域的H_∞控制器参数优化方法

基于控制理论 ,提出了一种具有预期闭环极点区域的H∞ 控制器参数优化设计方法 ,该方法设计中既考虑了H∞ 性能指标又兼顾了动态性能指标 ,克服了常规H∞ 设计方法中不稳定控制器的问题等不足 .实验结果表明 ,该方法具有计算简便、可实现性好、鲁棒性和动态品质良好、对模型参数变化的敏感性低等优点 .

垃圾焚烧电厂飞灰预稳定化技术实验研究

以常熟浦发垃圾电厂为研究对象,阐述了一种新型飞灰预稳定剂对于烟气脱酸、飞灰预稳定化的影响。结果表明:预稳定剂不但可以起到脱酸的效果,而且还可以对飞灰中重金属起到预稳定化作用,减少后续重金属螯合剂用量。同时减少石灰用量,使飞灰产生量降低。

FLAC^(3D)在潮湿环境史前考古土遗址直立探方稳定预判中的应用

潮湿环境中考古探方的失稳破坏不仅对遗址文物的保护不利,而且威胁着现场工作人员的人身安全。目前对潮湿环境下考古探方稳定性预判的研究较少。本文基于杭州潮湿地区的岩土参数采用FLAC3D数值模拟软件进行探方开挖前稳定性预判模拟计算。模拟探方为直立式,尺寸(长×宽×深)为5m×5m×2.4m。模拟发掘过程采取降排水措施。数值计算结果表明:(1)随开挖不断进行,坑壁水平位移逐渐增大,曲线形状呈"弓"型,水平位移由顶部至底部先增大到极值后减小,极值点位于距顶部1.75m的坑壁处。(2)最终安全系数为2.37。(3)得出了潜在滑移带所在位置,坑壁滑移带剪出口位于坑壁2.0m—2.4m处。计算结果可以为现场考古模拟发掘试验提供参考,为直立式考古探方稳定性预加固提供依据。

公路隧道钢拱架支护结构稳定性预判研究

本文在现场监测钢拱架内外侧翼缘应力变化的基础上,利用力学原理计算出钢拱架弯矩和轴力,综合考虑其受弯和应力状态,并结合隧道局部坍塌发生特点,进行安全分级、预判支护结构稳定性。结果表明,基于钢拱架应力监测的稳定性预判方法既能显示初支稳定性级别,又能反映钢拱架内力变化规律,且具有较高的灵敏度,可以提前发现失稳趋势,以便采取措施应对局部坍塌。

紧急功率支援下自适应重合闸附加稳定控制策略

能源分布和负荷需求逆向分布特征促成了我国形成多个大规模电力电能外送系统,在非预期大扰动下会出现系统首摆失稳且自适应重合闸仍难以改善系统稳定性的局面。基于此,提出了一种紧急功率支援下自适应重合闸附加稳定控制策略。首先分析了系统首摆失稳的场景以及失稳条件,并提出了基于功角超实时预测的首摆稳定性预判方法,论证了长时间要求的预测最优阶数。然后结合直流通道提供紧急功率支援能够消纳系统不平衡能量,提出基于超前预控的自适应重合闸附加稳定控制策略。结合失稳判断,分析预判控制时序。基于紧急功率支援协同最佳重合闸时间最大程度上减小了系统功角摇摆,解决了瞬时性故障首摆失稳时重合闸方案的缺失问题。最后,基于PSCAD/EMTDC建立大规模电力外送模型,仿真验证了所提自适应重合闸附加稳定控制策略的有效性。

基于广域响应的暂态稳定在线预判控制系统

现有的安全稳定控制策略是基于离线计算的预想方式和故障集,难以全面涵盖电网所有的特殊运行方式。在分析比较现有基于广域响应的暂态失稳判据的基础上,利用电力系统发生严重故障后发电机功角和振荡中心电压的同调变化关系,提出了一种计及振荡中心电压轨迹时间积分的暂态稳定判别技术,采用集中式控制结构方案,研发了基于广域响应的暂态稳定在线预判控制系统,实现了不依赖模型的电力系统暂态稳定实用化快速判别,并成功应用于贵州六盘水北部电网,投运至今运行正常,为电网严重故障时的紧急控制提供支持。

预燃式火焰稳定器高空低压试验研究

在二元燃烧试验设备和扇形燃烧试验设备上,模拟发动机高空低压状态,分别进行预燃式火焰稳定器及带径向稳定器的预燃式火焰稳定器的点火性能与稳定燃烧性能试验,得到预燃式火焰稳定器在安装径向稳定器前后的性能曲线。从结构参数和气动参数两方面出发,对这些曲线进行比较和分析,总结预燃式火焰稳定器的工作性能。

地沟油预酯化乳化液制备及其稳定性研究

实验采用预酯化油、复配型乳化剂以及适当的助溶剂制各地沟油皇预酯化油一甲醇乳化液，结果显示该乳化液具有较好的稳定性。

结合光流法和卡尔曼滤波的视频稳像算法

针对手机拍摄过程中产生的视频抖动问题,提出了一种基于光流法和卡尔曼滤波的视频稳像算法。首先通过光流法预稳定抖动视频,对其生成的预稳定视频帧进行Shi-Tomasi角点检测,并采用LK算法跟踪角点,再利用RANSAC算法估计相邻帧间的仿射变换矩阵,由此计算得出原始相机路径;然后通过卡尔曼滤波器优化平滑相机路径,得到平滑相机路径;最后由原始相机路径与平滑路径的关系,计算相邻帧间的补偿矩阵,再利用补偿矩阵对视频帧逐一进行几何变换,由此得到稳定的视频输出。实验表明,该算法在处理6大类抖动视频时均有较好的效果,其中稳像后视频的PSNR值相比原始视频的PSNR值约提升了6.631 dB,视频帧间的结构相似性SSIM约提升了40%,平均曲率值约提升了8.3%。

衣康酸含量对聚丙烯腈热行为的影响(英文)

共聚单体含量是影响PAN树脂在预氧化过程中反应特征的因素之一,通过热失重、差示扫描量热和X 射线衍射法探讨了衣康酸含量对共聚PAN的热失重、放热量、环化速度的影响。结果表明:衣康酸含量的质量分数从1.4%增加至4.3%时,共聚PAN在预氧化过程中放热量、热失重逐步降低;当衣康酸含量的质量分数超过4.3%时,其放热量和热失重逐渐增加。含4.3%衣康酸的聚丙烯腈树脂有最小的热失重、放热量和较低的环化速度。

Preconditioned BiCGSTAB algorithm and its applications to eddy current solutions

A new favorable iterative algorithm named as PBiCGSTAB （preconditioned bi-conjugate gradient stabilized） algorithm is presented for solving large sparse complex systems. Based on the orthogonal list, the special technique of only storing non-zero elements is carried out. The incomplete LU factorization without fill-ins is adopted to reduce the condition number of the coefficient matrix. The BiCGSTAB algorithm is extended from the real system to the complex system and it is used to solve the preconditioned complex linear equations. The locked-rotor state of a single-sided linear induction machine is simulated by the software programmed with the finite element method and the PBiCGSTAB algorithm. Then the results are compared with those from the commercial software ANSYS, showing the validation of the proposed software. The iterative steps required for the proposed algorithm are reduced to about one-third, when compared to the BiCG method, therefore the algorithm is fast.

Is the ratio of apoB/apoA-1 the best predictor for the severity of coronary artery lesions in Chinese diabetics with stable angina pectoris？ An assessment based on Gensini scores

Background There is a paucity of data about the best lipid ratio predicting the severity of coronary artery disease （CAD） in patients with diabetes mellitus. We determined the relationship between five conventional lipid ratios and the extent of coronary artery lesions in Chinese Type 2 diabetics with stable angina pectoris （SAP）. Methods A prospective cohort study within 373 type 2 diabetic patients diag- nosed with stable CAD by coronary angiography was performed. All patients were classified into three groups according to the tertiles of Gensini scores （GS, low group 〈 8 points n = 143; intermediate group 8-28 points, n = 109; high group 〉 28 points, n = 121）. Association between the ratios of apolipoprotein （apo） B and apoA-1, total cholesterol and high density lipoprotein cholesterol （TC/HDL-C）, triglycerides and HDL-C （TG/HDL-C）, low density lipoprotein cholesterol and HDL-C （LDL-C/HDL-C）, Non-HDL-C/HDL-C and GS were evaluated using the receivers operating characteristic （ROC） curves and multivariate logistic regression models. Results The ratio of apoB/apoA-1, TC/HDL-C, LDL-C/HDL-C, and Non-HDL-C/HDL-C were correlated with Gensini scores. Area under the ROC curves for predicting high Gensini scores in the ratios of apoB/apoA-1, TC/HDL-C, LDL-C/HDL-C and Non-HDL-C/HDL-C were 0.62, 0.60, 0.59 and 0.60, respec- tively （P 〈 0.005 for all）. According to multivariate logistic regression analysis after adjusted with demographic characteristic and other lipid parameters, the ratio of apoB/apoA-1 is qualified as an independent discriminator for the severity of CAD. However, after fiu-ther adjusting different baseline variables, such as left ventricular ejective fraction, hemoglobin Alc, leukocytes count and serum creatinine, none of the above lipid ratios remained. Conclusions Compared with other lipid parameters, the ratio of apoB/apoA-1 appears to be more significantly correlated with the extent of coronary artery lesions in Chinese diabetics, but it was not an independent predictor in these settings.

Robustly stable model predictive control based on parallel support vector machines with linear kernel

Robustly stable multi-step-ahead model predictive control (MPC) based on parallel support vector machines (SVMs) with linear kernel was proposed. First, an analytical solution of optimal control laws of parallel SVMs based MPC was derived, and then the necessary and sufficient stability condition for MPC closed loop was given according to SVM model, and finally a method of judging the discrepancy between SVM model and the actual plant was presented, and consequently the constraint sets, which can guarantee that the stability condition is still robust for model/plant mismatch within some given bounds, were obtained by applying small-gain theorem. Simulation experiments show the proposed stability condition and robust constraint sets can provide a convenient way of adjusting controller parameters to ensure a closed-loop with larger stable margin.

Telomerase activity in colorectal cancer,prognostic factor and implications in the microsatellite instability pathway

AIM： To determine whether the telomerase activity is related to the Microsatellite instability （MSI） genetic pathway and whether it means a difference in the survival.METHODS： The population consisted of 97 colorectal cancer patients. MSI determination was performed in accordance with the NCI criteria using PCR and Genescan. Telomerase activity was determined by the TRAP-assay, an ELISA procedure based on the amplification of telomeric repeat sequences.RESULTS： 6.2% showed high MSI （MSI-H）, 10.3% showed low MSI （MSI-L） and 83.5% did not show this alteration （MSS）. Positive telomerase activity was detected in 92.8% of the patients. 83.3% of MSI-H tumors showed positive telomerase against 93.8% of MSS tumors. In the overall survival analysis the absence of telomerase activity conferred a better prognosis.CONCLUSION： Previous works have shown that tumors which develop via the MSI pathway present a better prognosis. No link between telomerase activity and MSl status is observed, although sample sizes are small. Patients with telomerase negative tumors had better overall survival than patients with telomerase positive tumors.

Developments and prospects of microseismic monitoring technology in underground metal mines in China

Microseismic monitoring technology has become an important technique to assess stability of rock mass in metal mines.Due to the special characteristics of underground metal mines in China,including the high tectonic stress,irregular shape and existence of ore body,and complex mining methods,the application of microseismic technology is more diverse in China compared to other countries,and is more challenging than in other underground structures such as tunnels,hydropower stations and coal mines.Apart from assessing rock mass stability and ground pressure hazards induced by mining process,blasting,water inrush and large scale goaf,microseismic technology is also used to monitor illegal mining,and track personnel location during rescue work.Moreover,microseismic data have been used to optimize mining parameters in some metal mines.The technology is increasingly used to investigate cracking mechanism in the design of rock mass supports.In this paper,the application,research development and related achievements of microseismic technology in underground metal mines in China are summarized.By considering underground mines from the perspective of informatization,automation and intelligentization,future studies should focus on intelligent microseismic data processing method,e.g.,signal identification of microseismic and precise location algorithm,and on the research and development of microseismic equipment.In addition,integrated monitoring and collaborative analysis for rock mass response caused by mining disturbance will have good prospects for future development.

Left atrial area index predicts adverse cardiovascular events in patients with unstable angina pectoris

Background The left atrial size has been considered as a useful marker of adverse cardiovascular outcomes. However, it is not well known whether left atrial area index （LAAI） has predictive value for prognosis in patients with unstable angina pectoris （UAP）. This study was aimed to assess the association between LAAI and outcomes in UAP patients. Methods We enrolled a total of 391 in-hospital patients diag- nosed as UAP. Clinical and echocardiographic data at baseline were collected. The patients were followed for the development of ad- verse cardiovascular （CV） events, including hospital readmission for angina pectoris, acute myocardial infarction （AMI）, congestive heart failure （CHF）, stroke and all-cause mortality. Results During a mean follow-up time of 26.3±8.6 months, 98 adverse CV events occurred （84 hospital readmission for angina pectoris, four AMI, four CHF, one stroke and five all-cause mortality）. In a multivariate Cox model, LAAI [OR： 1.140, 95% CI： 1.01±1.279, P = 0.026], diastolic blood pressure （OR： 0.976, 95% CI： 0.956-0.996, P = 0.020） and pulse pressure （OR 1.020, 95% CI： 1.007-1.034, P = 0.004） were independent predictors for adverse CV events in UAP patients. Conclusions LAAI is a predictor of adverse CV events independent of clinical and other echocardiographic parameters in UAP patients.

Study of Slope Reinforcement Force Based on FLAC

A slope will slide if the unbalanced force does not tend to zero when the stability of the slope is analyzed with the help of FLAC. Thus the ultimate reason of slope sliding is the unbalanced force determined by FLAC. The slope will remain stable if the unbalanced force is counterbalanced by a reinforcement force which is produced by a suitable reinforcement method. In this paper, the stability of the slope was analyzed by using FLAC, and the unbalanced force of the slope was obtained through the FISH function in FLAC. According to the equilibrium conditions, the relationship between the reinforcement force and unbalanced force was derived and accordingly the reinforcement force was determined. The reinforcement design was adopted by using pre-stressed anchor bars on the basis of the reinforcement force. An example is used to show that the effect of slope reinforcement based on the reinforcement force is safe and economical. The method doesn＇t need to suppose a sliding surface to obtain the reinforcement force, and it is also clear in physical meaning. So this method realized the organic unification of the stability analysis and the slope reinforcement.

Study on gob-side entry retaining in fully-mechanized longwall with top-coal caving and its application

Based on the engineering background of gob-side entry retaining in fully-mechanized longwall with top coal caving(GER-FLTC) on N2105 working face of Yuwu coal mine, by adopting the methods of theoretical analysis and numerical calculation, the control techniques of surrounding rocks in GER-FLTC working face are studied in this paper. The two main difficulties of stability of surrounding rocks at gob-side retained entry in fully-mechanized longwall working face are the stability control of top coal and control of large deformation of GER-FLTC working face. Interaction mechanical model between roofing and roadside backfilling in GER-FLTC is established and the equations for the calculation of roof-cutting resistance of roadside backfilling are derived. Results of numerical calculation show that the damage zones of top coal can be categorized into the delaminating zone of top coal above the backfilling, tensile damage zone of top coal above the retained roadway and shear damage zone of the upper rib of the solid coal. Stability control of top coal is the critical part to success of GER-FLTC. With consideration of large deformation of surrounding rocks of gob-side retained entry in fully-mechanized longwall, the support technique of‘‘roofing control and wall strengthening'' is proposed where high strength and highly prestressed anchor rods and diagonal tensile anchor cables support are used for top coal, high strength and highly prestressed yielding anchor rod support is used for solid coal and roadside prestressed load-carrying backfilling is constructed by high-water material, in order to maintain the integrity of the top coal, transfer load, high resistance yielding load-carrying of solid coal, roof-cutting of roadside backfilling and support,and to achieve GER-FLTC. Results from this study are successfully applied in engineering practice.

Predicting the Rainfall-Triggered Landslides in a Forested Mountain Region Using TRIGRS Model

Landslides are natural disasters which can pose a serious threat to human and property in many areas around the world. The Transient Rainfall Infiltration and Grid-based Regional Slope-stability (TRIGRS) model was used to investigate the rainfall-induced shallow landslides in a forested mountain region, Korea. Various input data for TRIGRS model include time-varying rainfall, topographic characteristics, soil depth, material strength, and hydraulic properties. A series of calculations were conducted in determining the slope stability over the Jangheung region in Korea during the storm occurred on August 6, 1998. The results show that TRIGRS model captured about 64.1% of landslides that were extracted from the IKONOS2 imageries. The model demonstrated how the factor of safety changed with time during a storm considering both the transient and spatial responses of pore water pressure in its slope stability calculation.

Effect of pre-calcination for modified CaO-based sorbents on multiple carbonation/calcination cycles

In the present work,the effect of pre-calcination on carbonation conversion and cyclic stability of modi fied CaObased sorbent was investigated by thermogravimetric analyzer(TGA).The modi fied CaO-based sorbents with CaAc_2 as precursor were respectively doped with different elements(Mg,Al,Ce,Zr and La).The speci fic surface area,pore volume and pore size distribution were tested by N_2 isothermal adsorption measurements.The phase compositions of sorbents were characterized by X-ray diffraction(XRD).The results showed that the cyclic stabilities of the sorbents were improved by pre-calcination.The pre-calcination was conducted at 900°C for 5 h in air by the muf fle furnace.With pre-calcination,the cyclic stabilities of sorbents could be as high as 96% after 22 cycles,such as CaO-Al,CaO-Ce and CaO-La.After contact with air,the carbonation conversions of spent sorbents with pre-calcination suddenly increased by about one-sixth due to the change of channel structure by hydration.Both the cyclic stability of sorbent and the durability of reactivation were related to the structural stability of sample,especially the stability of mesopores between 2 nm and 5.5 nm.The present work also provided an easy and low-cost method for reactivating the spent CaO-based sorbents.