强震成功预报的曙光

20世纪50年代以来,我国30多次成功预报了中、强地震的发生;近加年来国外有些地震学家对几次强震预测失败感到失望,逐渐将地震研究的主攻方向转变为对建筑物抗震能力的鉴定、加强建筑物抗震措施和建立现代数字台网,以便迅速准确确定强震的发生地点,可以即刻到现场救援;国内地震界部分地震学家受他们的悲观情绪的影响,也放弃了对强震预报的努力.所幸的是部分专业和业余地震学家仍在强震预报领域做出了不懈的努力,取得了可喜的成绩.     

长江三峡坝区地壳稳定性研究

长江三峡大坝座落于黄陵断块南端由闪长花岗岩组成的完整岩体上。黄陵断块作为中国内陆的次级板块具有典型的双层结构（结晶基底和沉积盖层），自印支运动形成以来一直呈持续、缓慢的整体抬升，断块除向东南轻微倾斜外，内部构造变形不明显。断块为多条活动构造所围限，其中近南北向的远安和仙女山两条深大断裂为主要强震发生带。远安断裂带为豫西、鄂西、湘西山地和南阳、江汉、洞庭盆地的一条区域性分界线，全长约1000 km，该断裂带历史上曾发生过两次6.5级地震（常德、南阳），两次地震震中相距约500km；仙女山断裂带沿香溪河向北延伸终止于青峰断裂，向南越过渔洋关后，形迹不明，全长达220 km，该断裂带具有发生6.0级地震的构造条件。大坝可能遭遇到的地震危险主要来自这两条强震发生带，对大坝的影响烈度预计为6°～7°，水平峰值加速度0.1～0.15g。     

新疆克孜尔水库工程抗震研究的初探

地震工程学的发展是依赖强震监测工作。强震监测的根本任务是利用强震加速度仪来监测地震时地面运动的全过程以及在其作用下的结构反应情况。这是取得地震破坏作用和抗震性能认识的来源。它不仅为确定设计地震动参数和采取工程措施提供定量数据和理论依据,同时又可检验抗震设计理论和工程措施是否符合实际,加深人们对抗震客观规律的认识,不断推动地震工程学的发展。     

基于非线性静、动力方法的RC简支梁桥连梁装置参数优化研究

连梁拉杆装置是防止强震下RC梁式桥纵向落梁的有效措施,需要对其合理刚度取值进行研究。以典型的铁路RC简支梁桥为对象,采用基于FEMA440性能点轨迹法的能力谱分析方法,以现行《铁路工程抗震设计规范》设计谱及汶川地震动为需求,讨论了不同的场地类型和设防烈度下连梁拉杆的最优刚度分布。研究表明,场地类型对连梁装置刚度取值无显著影响,在8度罕遇烈度设防的四种场地下,连梁装置的刚度均可在0.05~0.15倍的梁体线刚度范围内取值,可有效抑制墩、梁相对位移及桥梁整体地震响应。设防烈度对刚度取值有显著影响,当PGA不超过0.2g时,可不予设置;当PGA为0.4g和0.6g时,连梁拉杆的合理刚度可分别取为0.1倍和0.2倍的梁体线刚度。采用非线性动力时程方法验证了上述结论的合理可靠性,可供桥梁抗震设计及规范修编参考     

近断层强震记录基线校正的改进方法

基于Iwan两段式校正方法的原理,引入参数“时移斜率比k i”和“校正后位移的最大平坦度f”来确定强震段偏移开始时间t 1和结束段偏移的开始时间t 2,引入参数“均方根偏差RMSD”来选择位移末尾部分拟合函数的次数,提出了近断层强震记录基线校正的改进方法。应用该方法对芦山地震和汶川地震共8个近断层台站的强震记录进行基线校正处理获取了永久位移。结果表明,获得的永久位移与强震台站附近的GPS台站观测的同震位移吻合较好,永久位移与GPS观测结果的比在0.57~1.72,均值为0.99。在一定程度上减少了主观经验对于基线校正结果带来的不确定性。同时对比分析了7种基线校正方法对峰值地面运动参数和永久位移的影响,PGA和PGV受不同基线校正方法的影响很小,但是不同的基线校正方法对PGD和永久位移的影响非常大。     

与震中烈度相关的地震动功率谱参数

利用震中烈度与强震持续时间的统计关系将抗震设计规范中的设计反应谱转换成功率谱，并用指定的功率谱模型拟合得到与设计反应谱对应的功率谱模型参数，强震持时与地震动最大幅值的越超概率有关，相同的超越概率下，地震动统计统计参数应该与持续时间有关，本文由震中烈度反映了二者的关系。     

不同地震作用方向下混凝土核心筒基于增量动力分析的抗震性能评估

强震作用下,核心筒对混合结构发生破坏乃至倒塌有着重要影响。选择合适的地震输入,进行核心筒在双向或多向地震作用下的地震反应分析是值得深入研究的。采用动力时程分析方法,通过不同方向地震作用与单向地震作用下混凝土核心筒的地震效应对比可知,在进行结构设计时,大震作用下,斜向地震作用下的内力要明显偏大,仅考虑单向输入的水平加速度的设计结果会偏于不安全。并通过输入与Y轴45°斜向地震记录基于单条地震记录的增量动力分析方法（IDA方法）对核心筒进行抗震性能评估。结果表明,斜向地震输入对核心筒IDA曲线有一定影响,但各性能点对应的量化位移指标与Y向单条地震输入时相差不大。     

基于PSHA的核电厂近断层抗震设计谱构建方法

核电是一种高效、清洁的能源,随着核电厂未来向内陆区的发展,其可能会遭遇到近断层地震动的影响,但是目前我国核电厂抗震规范设计谱并未考虑近断层地震动。该文首先基于大量实际近断层脉冲型和相应无脉冲地震动记录,研究了脉冲对反应谱的放大效应,建立了修正的近断层脉冲放大系数模型;继而将地震动脉冲效应引入到近断层概率地震危险性分析中,并基于设定断层模型,给出了不同场地类型的一致危险性反应谱;通过对地震危险性结果的分解,分析了对场地最危险震级和距离,并将结果引入地震动衰减关系中得到设计谱,最后通过近断层脉冲放大系数对设计谱进行修正,得到考虑近断层脉冲效应的核电厂抗震设计谱。通过研究,建立了一种基于概率地震危险性分析框架下,考虑近断层脉冲型地震动的工程场地核电厂抗震设计谱的构建方法。     

结构时程分析中强震记录选取研究综述

该文论述了近年来国内外在结构抗震时程分析中输入强震记录选取的各种方法,对评判指标的选取及样本容量的确定进行了分类梳理和评述。震级、震中距、场地等地震信息常作为选波的第一评判指标,而目标谱及其他地震动强度指标则作为第二评判指标。地震动强度指标已总结出数十种,它们与结构反应的相关性及其在选波研究中的优越性认识不一。以反应谱为目标进行匹配、缩放及选择的方法（目标谱选波法）,成为目前最主流的方法。目标谱的种类较多,最广泛采用的是规范设计谱,工程应用比较方便;条件均值谱方法精度较高,但如何将条件均值谱与我国规范接轨,仍需深入研究。结构反应均值估计中,反映强震记录反应谱与目标谱匹配程度的误差指标及缩放方法的取用,应力求能够选出谱形匹配较优的强震记录。随着基于性能抗震理念的深入及地震危险性概率分析方法的逐渐完善,结构反应的估计也从均值发展到概率分布,其所需的样本容量及所采用的评判指标研究仍需进一步深入。     

跨断层简支钢箱梁桥的概率性地震损伤特性研究

以跨越走滑断层的简支钢箱梁桥为对象,同时考虑地震动和结构参数不确定性的影响,开展全桥结构在非一致激励下的增量动力分析,深入讨论了跨断层桥梁桥墩的概率性地震损伤特性。结果表明,结构参数不确定性的影响随着地震动增强而变大;对于紧邻断层桥墩,当断层滑冲强度为78.0 cm时,完全破坏的超越概率由均值模型的7.53%增大到随机模型的13.01%,说明强震下如不考虑结构参数不确定性的影响可能会低估结构的易损性。紧邻断层桥墩面临更高的地震损伤概率,当断层滑冲强度为52.0 cm时,四种损伤状态下非紧邻断层墩的超越概率分别为97.54%、88.51%、2.42%和0.06%,而紧邻断层墩分别为99.24%、99.15%、6.50%和0.28%。因此,应对跨断层桥梁紧邻断层桥墩的抗震设计予以更多关注,开展针对性抗震设计。     

Application of General Fractal Dimension to Coupling Fault Diagnosis

This paper presents the coucept of general and sensitive dimension,and also proposes the calculation formula of the general dimension least squares method.By calculating and analyzing the power spectrum and general dimension grom the fault sample,the relationship is achieved between sample status and the general simension from vibration signals of the equipment so as to provide reference to fault diagnosis.Furthermore,a correlation function of general dimension is proposed,and calculations are carried out for a monitor signal and samples signal.The diagnosis method based on fractal theory is effective through the concrete examples of the steam-electric generating set fault diagnosis,and the correlation coefficient of general dimension between a monitor signal and samples signal can improve the accuracy for fault diagnosis.     

The dawn of successful prediction of major earthquakes

Since 1949, Chinese scientists have successfully predicted occurrence of many major earthquakes, such as the Haicheng M7.3 event in 1975 and the Asian Game Village shock of 1990. In recent 20 years, however, some seismologists abroad have taken a disappointed and pessimistic view to earthquake prediction because of several failures. They suggest that the efforts should turn toward other fields, such as identification of building’s earthquake-proof capability, enhancement of house strength, and development of precise observational systems which will facilitate fast locating of future major temblors and emergent relief on site. Such a pessimistic feeling has also influence some Chinese researchers of the seismological community who attempted to give up efforts for earthquake prediction. Meanwhile other scientific workers are insisting in experiments and practices in this field and achieved some inspiring results. In this paper, we present several representative cases to illustrate that earthquakes are predictable under some conditions.     

深部裂缝带——一种新的地震构造样式

黄河黑山峡大柳树坝址、雅砻江锦屏普斯罗坝址及其他一些水电工程区，在勘探过程相继发现了一种新的地质构造现象——深部裂缝带，并且多出现在我国强震活跃地区和强震发生断裂带上，沿断裂带历史上强震活动频繁；深部裂缝带向地下延伸超过300m，远远超出地表卸荷带的影响深度，故与强地震作用时岩体构造动力效应密切相关；讨论了根据弹性波作用下岩体的动力学响应，阐述了深部裂缝带发生的地震学原因。     

An improved cuckoo search algorithm and its application in vibration fault diagnosis for a hydroelectric generating unit

This article presents an improved cuckoo search (ICS) algorithm based on the parametric adaptation mechanism and non-uniform mutation. In the ICS algorithm, the biased random walk operator is modified to take advantage of the neighbourhood information of the current solution, and then the control parameters of step size, discovery probability and scaling factor are directly integrated into the optimized problems. Meanwhile, the non-uniform mutation operation is used to adaptively tune the search step of the current optimal solution. To evaluate the feasibility and efficiency of the presented algorithm, three groups of benchmark test functions are employed to perform the validation analysis. Subsequently, to diagnose the vibration fault of a hydroelectric generating unit, a combinational model is built, which combines ICS with a back-propagation neural network (ICSBP). The experimental results indicate that ICS is competitive on the optimization problems, and the ICSBP approach can effectively improve the accuracy of vibration fault diagnosis for a hydroelectric generating unit.     

Multi-state systems with multi-fault coverage

The paper introduces a new model of fault level coverage for multi-state systems in which the effectiveness of recovery mechanisms depends on the coexistence of multiple faults in related elements. Examples of this effect can be found in computing systems, electrical power distribution networks, pipelines carrying dangerous materials, etc. For evaluating reliability and performance indices of multi-state systems with imperfect multi-fault coverage, a modification of the generalized reliability block diagram (RBD) method is suggested. This method, based on a universal generating function technique, allows performance distribution of complex multi-state series–parallel system with multi-fault coverage to be obtained using a straightforward recursive procedure. Illustrative examples are presented.     

Issues associated with two-shift operation of combined cycle generating plant

Abstract

Diverse experiences associated with two-shifting of conventional generating units are largely relevant to the ‘balance of plant’ in combined cycle generating units (CCGTs). Although two-shifting has adversely impacted upon reliability and availability, and incurred substantial additional maintenance costs on many conventional units, this has not been the case for all installations. Reference 1, for example, reports that four large coal-fired units, which have been extensively two-shifted for more than 15 years, have experienced no major and just a few minor problems attributable to many shutdown-startup cycles. These units are capable of more than 200,000 hours running with more than 6,000 starts; only a small additional maintenance cost is attributable to two-shifting.

Startups and shutdowns impose more onerous conditions on critical parts of many components of most fossil-fired generating plant than experienced when operating continuously at maximum rating (the steady-state condition at which unit and component design verification analysis is generally performed). The generic root cause of many of the major and the miscellany of lesser problems attributable to two-shifting has been a general omission by equipment designers, architect-engineers and purchasers to determine, during the design phase, (i) realistic transient conditions imposed on various components during unit startups and shutdowns. and (ii) the consequential life expenditure from cyclic thermal-mechanical cyclic loadings and other mechanisms of material degradation caused by mechanical load cycles.

It is feasible to design CCGTs capable of very extensive two-shifting without thermally induced failures in the balance of plant [2–4]. However, CCGTs do have additional difficulties to understand and manage by appropriate design and operation. For example, CCGTs:

have to consider the additional operational and cost implications associated with two-shifting the gas turbine (GT);

have more complex cycles, which are additional complications to operation during shutdowns and startups;

impose more severe conditions on the superheater and economizer of the HRSG during both the shutdown and startup process than is experienced in conventional boilers.

Therefore CCGTs require even more design attention than conventional units to enable them to twoshift without adversely impacting reliability and availability and without incurring excessive additional maintenance costs for the balance of plant.

For either a CCGT or conventional coal-fired generating plant, one of the requirements for troublefree two-shift operation is that all parts subjected to significant heating and/or cooling during CCGT startups and shutdowns require good thermal flexibility. Thermal flexibility in the critical parts of the plant is achieved by a combination of:

appropriate conceptual and detailed design of the key equipment; i.e., the GT, steam turbine (ST), and HRSG

appropriate design of key auxiliary systems which influence the conditions imposed on HRSG and ST;

unit operating procedures for CCGT shutdowns and startups that minimize thermal stresses in all critical parts of GT, ST and HRSG.

The importance of having good thermal flexibility to minimize distress from thermally-induced low cycle fatigue (LCF) caused by unit shutdowns and startups has been well-publicised. There have been many failures of tubes at attachments to superheater and economizer headers most of which are attributable to transient high stresses developed during startups (in some cases in less than 200 startups). Despite this, CCGTs continue to be installed with design weaknesses that would not be difficult nor costly to correct on a new installation, and operating procedures unnecessarily harmful to the HRSG continue to be widely used.

Good thermal flexibility is only one of the crucially important objectives for CCGTs intended for twoshifting. This paper discusses several other technical challenges to be overcome for a CCGT to provide high startup reliability without adverse impact on CCGT reliability and availability. It also addresses the minimum additional maintenance cost for the ‘balance of plant’ that is attributable to two-shifting.     

面向事务处理的容错计算机系统结构设计与实现

提出了一种面向事务处理的容错计算机体系结构,设计了基于三模冗余的仲裁器和仲裁算法。在集群中,利用中心结点故障检测机制,采用仲裁器得到了一个逻辑上高可靠的管理态结点,通过该结点可以实现系统快速故障诊断和故障恢复。实验结果表明：节点间故障检测时间小于2s,故障节点切换时间小于5s,该系统的故障检测、故障节点切换可以满足事务处理系统对可靠性的要求。     

光生酸剂光分解行为的研究

论文以对酸敏感的罗丹明B为示踪剂，通过采用分光光度法和荧光光谱法，建立了光生酸剂在溶剂中和在高分子薄膜中光分解行为的评价方法。研究结果表明，本研究提出的光生酸剂在溶液中和在高分子薄膜中产酸效率的评价方法切实可行，能够准确地定量评价光生酸剂的光化学反应和产酸行为，用这种测量方法可以评价现有的三嗪类与硫翁盐类光生酸剂的产酸优劣。     

Ω-代数遗传性的注记

探讨了Ω-代数的遗传性,即考察Ω-代数的生成元集的性质对Ω-代数自身性质的影响.证明了在一定条件下Ω-代数的交换性及从一个Ω-代数到另一个Ω-代数的同态映射都由Ω-代数的生成元集决定.