Optimal bounded control of first-passage failure of strongly non-linear oscillators under combined harmonic and white-noise excitations

A procedure for designing the optimal bounded control of strongly non-linear oscillators under combined harmonic and white-noise excitations for minimizing their first-passage failure is proposed. First, a stochastic averaging method for strongly non-linear oscillators under combined harmonic and white-noise excitations using generalized harmonic functions is introduced. Then, the dynamical programming equations and their boundary and final time conditions for the control problems of maximizing reliability and of maximizing mean first-passage time are formulated from the averaged Ito equations by using the dynamical programming principle. The optimal control law is derived from the dynamical programming equations and control constraint. Finally, the conditional reliability function, the conditional probability density and mean of the first-passage time of the optimally controlled system are obtained from solving the backward Kolmogorov equation and Pontryagin equation. An example is given to illustrate the proposed procedure and the results obtained are verified by using those from digital simulation. (C) 2003 Elsevier Ltd. All rights reserved.

An optimal theory for an expansion of flow quantities to capture the flow structures

An optimal theory on how database analysis to capture the flow structures has been developed in this paper, which include the POD method as its special case. By means of the remainder minimization method in the Sobolev space, for more general optimal conditions the new theory has the potential to overcome an inherent limitation of the POD method, i.e., it cannot be used to the situations in which the optimal condition is other than the inner product global one. As an example, using the new theory, the database of a two-dimensional flow over a backward-facing step is analyzed in detail, with velocity and vorticity bases.

New Keynesian Model Features that Can Reproduce Lead, Lag and Persistence Patterns

This paper uses a new method for describing dynamic comovement and persistence in economic time series which builds on the contemporaneous forecast error method developed in den Haan (2000). This data description method is then used to address issues in New Keynesian model performance in two ways. First, well known data patterns, such as output and inflation leads and lags and inflation persistence, are decomposed into forecast horizon components to give a more complete description of the data patterns. These results show that the well known lead and lag patterns between output and inflation arise mostly in the medium term forecasts horizons. Second, the data summary method is used to investigate a rich New Keynesian model with many modeling features to see which of these features can reproduce lead, lag and persistence patterns seen in the data. Many studies have suggested that a backward looking component in the Phillips curve is needed to match the data, but our simulations show this is not necessary. We show that a simple general equilibrium model with persistent IS curve shocks and persistent supply shocks can reproduce the lead, lag and persistence patterns seen in the data.

How Does the New Keynesian Monetary Model Fit in the U.S. and the Eurozone? an Indirect Inference Approach

This paper estimates a standard version of the New Keynesian monetary (NKM) model under alternative specifications of the monetary policy rule using U.S. and Eurozone data. The estimation procedure implemented is a classical method based on the indirect inference principle. An unrestricted VAR is considered as the auxiliary model. On the one hand, the estimation method proposed overcomes some of the shortcomings of using a structural VAR as the auxiliary model in order to identify the impulse response that defines the minimum distance estimator implemented in the literature. On the other hand, by following a classical approach we can further assess the estimation results found in recent papers that follow a maximum-likelihood Bayesian approach. The estimation results show that some structural parameter estimates are quite sensitive to the specification of monetary policy. Moreover, the estimation results in the U.S. show that the fit of the NKM under an optimal monetary plan is much worse than the fit of the NKM model assuming a forward-looking Taylor rule. In contrast to the U.S. case, in the Eurozone the best fit is obtained assuming a backward-looking Taylor rule, but the improvement is rather small with respect to assuming either a forward-looking Taylor rule or an optimal plan.

后台阶下游床面冲刷过程数值模拟研究

以床面瞬时剪应力作为泥沙起动及输运的水动力机制,建立了结构物周围复杂流场下床面局部冲刷的数学模型。并应用大涡模拟方法对后台阶下游三维湍流流动进行数值模拟,得到台阶下游床面瞬时剪应力的分布规律。为了确定床面瞬时剪应力与泥沙上扬通量的关系,先应用数学模型对不同模型参数下,冲刷开始后5分钟时台阶下游床面形状进行试算。通过试算与实验结果的比较,确定床面瞬时剪应力与泥沙上扬通量关系中需要的模型参数。进一步对冲刷开始后30分钟内台阶下游床面演化规律进行模拟,模拟结果与实验结果相符合。

激波管双爆轰驱动段性能的数值模拟研究

采用频散可控的耗散格式(DCD),求解Euler方程和一种改进的二阶段化学反应模型,对氢氧反向-正向双爆轰驱动段激波管进行了数值模拟.计算结果表明:当辅驱动段与主驱动段初始压力比小于临界值时,Taylor波仍会出现,但波扇夹角较单一前向爆轰驱动段小,入射激波马赫数衰减率变小;当初始压力比等于临界值时,主驱动段中的Taylor波完全被消除,入射激波马赫数不再衰减.当初始压力比大于临界值时,在主驱动段中能产生过驱动爆轰波,不仅Taylor波被完全消除,而且驱动能力较单一前向爆轰驱动段强

电潜泵井生产动态分析

提出了原油物性模拟的修正模型，其结果与PVT曲线具有良好的相关性。给出了电潜泵内流体温升及井筒中流体温度梯度的计算方法。通过引入井眼轨迹的描述与计算描述，成功地解决了弯曲井段的多相流计算问题，从而可以计算出任意井眼形状中的参数分布规律。在此基础上，借助于毛细管、动液面或泵特性测试资料，实现了对电潜泵井生产动态的模拟和分析，并在现场应用中收到了良好的效果。

Enirio-Aralar mendietako abereen eta basoen ustiapena aro berrian zehar

[EUS]Enirio-Aralarreko mendietako basoek ez dute XVIII. mendera arte ustiapen gogorrik jasango. Ordura arte Batasunetako biztanleek behar zuten egurra soilik ateratzen zuten, ia ustiapen industrialik gabe. XVIII. mendean, beheko aldeko hariztiak agortu zirenean, Enirio-Aralarreko pagoak hasi ziren ustiatzen ikatza, itsasontziak edo arma-kajoiak egiteko. Aldi berean, ordura arte “tokian tokiko” abeltzaintza izan zena, erdi trashumantzia bihurtu zen: kostaldeko eta inguruko artaldeak Enirio-Aralar mendietan hasi ziren uda ematen. Aipatutako bi faktoreek –basoaren ustiapenak eta kanpoko artaldeen etorrerak–, batik bat XVIII. mendearen bukaeran eta XIX. mendearen hasieran, Enirio-Aralarreko basoaren atzerakada eragin zuten. XIX eta XX. mendeetan zehar deforestazioa areagotu egin zen, bertako mendiei gaur egun ezagutzen dugun itxura eman arte.

脉冲液体射流泵性能的理论分析及数值计算

推导了以往复泵为脉冲发生装置的脉冲液体射流泵准二维性能方程及其时均性能方程,导出无因次惯性水头及惯性力项便于计算的表达式,并对脉冲液体射流泵时均性能进行了数值计算,计算结果与试验数据基本吻合,将数值计算的模拟曲线与恒定液体射流泵性能曲线进行对照,证明了采用脉冲射流作为工作动力能够大幅提高射流泵的效率.

Aquaculture Asia, Vol.13, No.4, pp.1-51, October-December 2008

Editorial An increasingly secure future for wastewater-fed aquaculture in Kolkata, India? by Peter Edwards. First culture-based fisheries growth cycle in Lao PDR is overwhelmingly encouraging, by Sena De Silva. Revival of abandoned shrimp farms in Krishna District of Andhra Pradesh, by National Centre for Sustainable Aquaculture (NaCSA). Growth of forward and backward industries linked with aquaculture in Kolleru Lake area, Andhra Pradesh, India, by A. K. Roy, G. S. Saha, P. Kumaraiah and N. Sarangi Effective marketing strategies for economic viability of prawn farming in Kuttanad, India, by Ranjeet K. and B. Madhusoodana Kurup. Applications of nutritional biotechnology in aquaculture, by S.D. Singh, S.K. Nayak, M. Sekar and B.K. Behera. Some technical and management aspects of catfish hatcheries in Hong Ngu district, Dong Thap province, Vietnam, by H. P. Hung, N. T. T. An, N. V. Trieu, D. T. Yen, U. Na-Nakorn, Thuy T. T. Nguyen. Nodavirus: An emerging threat to freshwater prawn farming, by Biju Sam Kamalam, J., Saravanan, S. and Ajith Stalin, J.L. Asia-Pacific Marine Finfish Aquaculture Network Magazine: Asian seabass farming: Brainstorming workshop and training in India. Comparative study for broodstock management of grey mullet (Mugil cephalus L.) in cages and earthen ponds with hormone treatment, by Nani Gopal Das, Md. Shahadat Hossain, Sushanta Bhattacharjee and Prabal Barua. Cultivation of gilthead sea bream (Sparus auratus L.) in low saline inland water of the southern part of Israel desert, by Samuel Appelbaum and A. Jesu Arockia Raj. Mariculture development opportunities in SE Sulawesi, Indonesia, by La Ode M. Aslan, Hotman Hutauruk, Armen Zulham,Irwan Effendy, Mhummaed Atid, Michael Phillips, Lars Olsen, Brendan Larkin, Sena S De Silva, Geoff Gooley. Improved hatchery and grow-out technology for marine finfish. NACA Newsletter

Survey of fish protective facilities at water withdrawal sites on the Snake and Columbia Rivers

Proliferation of water withdrawals and new pump intake and screen designs has occurred with the growth of irrigated agriculture along the Columbia and Snake Rivers. Concern for the protection of anadromous and resident fish populations resulted in formulation of a survey of the water withdrawal systems. The survey included distribution studies of juvenile fish near pump sites and field inspection of those sites to determine adequacy of screening for protection of fish. A total of 225 sites were inspected in 1979 and 1980, with a follow-up inspection of 95 sites in 1982. Results indicated a definite trend toward lack of concern for the condition of fish protective facilities. Only 4 out of 22 sites not meeting criteria in 1979 had been upgraded to acceptable conditions. Of more concern, 13 of the sites meeting criteria in 1979 were below criteria when reinspected in 1982. Some of the discrepancies included lack of protective screens, poorly maintained screens, and screens permitting excessive velocity that could result in impingement of larvae or small fish. A conclusion from these surveys is that if adequate protection for fish is to exist, screens for water withdrawals need to be properly installed, inspected, and maintained. (PDF file contains 40 pages.)

Molecular diagnosis of distal renal tubular acidosis in Tunisian patients: proposed algorithm for Northern Africa populations for the ATP6V1B1, ATP6V0A4 and SCL4A1 genes

Background: Primary distal renal tubular acidosis (dRTA) caused by mutations in the genes that codify for the H+ -ATPase pump subunits is a heterogeneous disease with a poor phenotype-genotype correlation. Up to now, large cohorts of dRTA Tunisian patients have not been analyzed, and molecular defects may differ from those described in other ethnicities. We aim to identify molecular defects present in the ATP6V1B1, ATP6V0A4 and SLC4A1 genes in a Tunisian cohort, according to the following algorithm: first, ATP6V1B1 gene analysis in dRTA patients with sensorineural hearing loss (SNHL) or unknown hearing status. Afterwards, ATP6V0A4 gene study in dRTA patients with normal hearing, and in those without any structural mutation in the ATP6V1B1 gene despite presenting SNHL. Finally, analysis of the SLC4A1 gene in those patients with a negative result for the previous studies. Methods: 25 children (19 boys) with dRTA from 20 families of Tunisian origin were studied. DNAs were extracted by the standard phenol/chloroform method. Molecular analysis was performed by PCR amplification and direct sequencing. Results: In the index cases, ATP6V1B1 gene screening resulted in a mutation detection rate of 81.25%, which increased up to 95% after ATP6V0A4 gene analysis. Three ATP6V1B1 mutations were observed: one frameshift mutation (c.1155dupC; p.Ile386fs), in exon 12; a G to C single nucleotide substitution, on the acceptor splicing site (c.175-1G > C; p.?) in intron 2, and one novel missense mutation (c. 1102G > A; p. Glu368Lys), in exon 11. We also report four mutations in the ATP6V0A4 gene: one single nucleotide deletion in exon 13 (c.1221delG; p. Met408Cysfs* 10); the nonsense c.16C > T; p.Arg6*, in exon 3; and the missense changes c.1739 T > C; p.Met580Thr, in exon 17 and c.2035G > T; p.Asp679Tyr, in exon 19. Conclusion: Molecular diagnosis of ATP6V1B1 and ATP6V0A4 genes was performed in a large Tunisian cohort with dRTA. We identified three different ATP6V1B1 and four different ATP6V0A4 mutations in 25 Tunisian children. One of them, c.1102G > A; p.Glu368Lys in the ATP6V1B1 gene, had not previously been described. Among deaf since childhood patients, 75% had the ATP6V1B1 gene c. 1155dupC mutation in homozygosis. Based on the results, we propose a new diagnostic strategy to facilitate the genetic testing in North Africans with dRTA and SNHL.

Multi-drug resistance profiles and the genetic features of Acinetobacter baumannii isolates from Bolivia

Introduction: Acinetobacter baumannii is opportunistic in debilitated hospitalised patients. Because information from some South American countries was previously lacking, this study examined the emergence of multi-resistant A. baumannii in three hospitals in Cochabamba, Bolivia, from 2008 to 2009. Methodology: Multiplex PCR was used to identify the main resistance genes in 15 multi-resistant A. baumannii isolates. RT-PCR was used to measure gene expression. The genetic environment of these genes was also analysed by PCR amplification and sequencing. Minimum inhibitory concentrations were determined for key antibiotics and some were determined in the presence of an efflux pump inhibitor, 1-(1-napthylmethyl) piperazine. Results: Fourteen strains were found to be multi-resistant. Each strain was found to have the bla(OXA-58) gene with the ISAba3-like element upstream, responsible for over-expression of the latter and subsequent carbapenem resistance. Similarly, ISAba1, upstream of the bla(ADC) gene caused over-expression of the latter and cephalosporin resistance; mutations in the gyrA(Ser83 to Leu) and parC (Ser-80 to Phe) genes were commensurate with fluoroquinolone resistance. In addition, the adeA, adeB efflux genes were over-expressed. All 15 isolates were positive for at least two aminoglycoside resistance genes. Conclusion: This is one of the first reports analyzing the multi-drug resistance profile of A. baumannii strains isolated in Bolivia and shows that the over-expression of thebla(OXA-58), bla(ADC) and efflux genes together with aminoglycoside modifying enzymes and mutations in DNA topoisomerases are responsible for the multi-resistance of the bacteria and the subsequent difficulty in treating infections caused by them.

Der Haftwasseranteil bei Heringsanlandungen über Bandwaagen

In 2004 the fish processing company Euro-Baltic Fischverarbeitungs GmbH Mukran, went into operation on the Isle of Rügen at the Baltic coast of Germany. About 20 % of the herring landed there is discharged from the cutters into the processing plant by pipes, driven by pumps, in case that the landed volume exceeds 10 t fresh weight. In such case the herring is transported in water suspension by means of a pressure-vacuum suction pump system into containers and further transported via conveyer belt to a flowscale. During this process most of the water runs off. It is however unknown how much water remains with the fish and is eventually weighted as fish. To estimate this proportion the mixture of water and fish was stored in special transport containers, which allow the measurement of the run-off. As a result the study shows that on average 2 % of weight measured by the tape scale is water. Along with this factors were determined which influence the variability of the proportion of water.