Development of a servo-hydraulic earthquake actuator for the Cambridge Turner beam centrifuge

Dynamic centrifuge modelling has been carried out at Cambridge since the late 1970s. Over this period, three different mechanical earthquake actuators were developed. In this paper the development of a new servo-hydraulic earthquake actuator is described. The basic design principles are explained along with the need to carry out these designs to match the existing services and systems of the 35 year old Turner beam centrifuge at Cambridge. In addition, some of the features of the Turner beam centrifuge are exploited in the design of this new earthquake actuator. The paper also explains the mechanical fabrication of the actuator and the control systems that were developed in order to generate real earthquake motions. Finally, the performance of this new servo-hydraulic earthquake actuator is presented and assessed based on a wide range of earthquake input motions.

The flow of steel into the construction sector

Half of the world's annual production of steel is used in constructing buildings and infrastructure. Producing this steel causes significant amounts of carbon dioxide to be released into the atmosphere. Climate change experts recommend this amount be halved by 2050; however steel demand is predicted to have doubled by this date. As process efficiency improvements will not reach the required 75% reduction in emissions per unit steel output, new methods must be examined to deliver service using less steel production. To apply such methods successfully to construction, it must first be known where steel is used currently within the industry. This information is not available so a methodology is proposed to estimate it from known data. Results are presented for steel flows by product for ten construction sectors for both the UK and the world in 2006. An estimate for steel use within a 'typical' building is also published for the first time. Industrial buildings and utility infrastructure are identified as the largest end-uses of steel, while superstructure is confirmed as the main use of steel in a building. The results highlight discrepancies in previous steel estimates and life-cycle assessments, and will inform future research on lowering demand for steel, hence reducing carbon emissions. © 2012 Elsevier B.V. All rights reserved.

Dwell time effect in peeling PSA laminates

Air, trapped interfacially between the adhesive and the substrate, can have a detrimental effect on the peel strength of bonds formed by a PSA and relatively impermeable adherends. If the adhesive wets the substrate surface so that the contact angle is small then the forces of the surface tension within the adhesive can lead to the gradual expulsion of these pockets of air and thereby to the enhancement of the peel strength-the dwell-time effect. Using a high-performance PSA transfer tape it has been found that this strengthening effect may operate over many thousands of hours. With increasing hydrophobicity of the surfaces, this effect can be suppressed and a poor peel strength remains essentially constant with time. The observed rates at which the peel strength increases are quantitatively consistent with diffusion of entrapped air out of the interface. © 2012 Copyright Taylor and Francis Group, LLC.

The design of multi-element airfoils through multi-objective optimization techniques

This paper presents the development and the application of a multi-objective optimization framework for the design of two-dimensional multi-element high-lift airfoils. An innovative and efficient optimization algorithm, namely Multi-Objective Tabu Search (MOTS), has been selected as core of the framework. The flow-field around the multi-element configuration is simulated using the commercial computational fluid dynamics (cfd) suite Ansys cfx. Elements shape and deployment settings have been considered as design variables in the optimization of the Garteur A310 airfoil, as presented here. A validation and verification process of the cfd simulation for the Garteur airfoil is performed using available wind tunnel data. Two design examples are presented in this study: a single-point optimization aiming at concurrently increasing the lift and drag performance of the test case at a fixed angle of attack and a multi-point optimization. The latter aims at introducing operational robustness and off-design performance into the design process. Finally, the performance of the MOTS algorithm is assessed by comparison with the leading NSGA-II (Non-dominated Sorting Genetic Algorithm) optimization strategy. An equivalent framework developed by the authors within the industrial sponsor environment is used for the comparison. To eliminate cfd solver dependencies three optimum solutions from the Pareto optimal set have been cross-validated. As a result of this study MOTS has been demonstrated to be an efficient and effective algorithm for aerodynamic optimizations. Copyright © 2012 Tech Science Press.

Numerical simulation of single-stream jets from a serrated nozzle

Hybrid large-eddy type simulations for cold jet flows from a serrated nozzle are performed at an acoustic Mach number Ma ac = 0.9 and Re = 1.03×10 6. Since the solver being used tends towards having dissipative qualities, the subgrid scale (SGS) model is omitted, giving a numerical type LES (NLES) or implicit LES (ILES) reminiscent procedure. To overcome near wall streak resolution problems a near wall RANS (Reynolds averaged Navier-Stokes) model is smoothly blended to the LES making a hybrid RANS-ILES. The geometric complexity of the serrated nozzle is fully considered without simplification or emulation. An improved but still modest hexahedral multi-block grid with circa 20 million grid points (with respect to 12.5 million in Xia et al.; Int J Heat Fluid Flow 30:1067-1079, 2009) is used. Despite the modest grid size, encouraging and improved results are obtained. Directly resolved mean and second-order fluctuating quantities along the jet centerline and in the jet shear layer compare favorably with measurements. The radiated far-field sound predicted using the Ffowcs Williams and Hawkings (FW-H) surface integral method shows good agreement with the measurements in directivity and sound spectra. © 2011 Springer Science+Business Media B.V.

底栖藻类对氮、磷去除效果研究

通过模拟实验探讨了污水处理中底栖藻类的群落结构、生长状况及其对氮(N)、磷(P)的去除能力。实验期间,被试藻类(丝状绿藻占优势)在污水中生长良好,培养5 d后收获的藻类生物量可达14.36±0.72 g;污水总氮(TN)、总磷(TP)含量分别由36.97±0.26 m g.L-1、2.88±0.02 m g.L-1降至1.44±0.09 m g.L-1、0.07±0.01 m g.L-1,对氨氮(NH4-N)和硝氮(NO3-N)的去除率亦达95%以上;藻体总凯氏氮(TKN)和TP含量分别为5.75±0.2

天然水体中微囊藻毒素归宿的初步研究

微囊藻毒素是有毒蓝藻释放的肝毒性代谢物,对环境和人们健康具有潜在危害,成为各国普遍关注的热点,并已列入我国地表水环境质量特定检测项目。在暴发严重蓝藻水华的滇池水环境治理工程中,对水华污染水体中微囊藻毒素的含量进行了全年监测,结果表明水样中微囊藻毒素含量的变化范围为0.17～0.82μg/L,比水体中蓝藻生物量的藻毒素含量低了至少一个数量级。为研究水体中藻毒素的归宿,通过有关微囊藻毒素的吸附、光降解、微生物降解等一系列现场和实验室研究,结果表明光降解是滇池水体中微囊藻毒素浓度降低的主要途径,同时微生物降解、

企鹅珍珠贝同工酶酶谱特征及其遗传分析

采用垂直板状聚丙烯酰胺梯度凝胶电泳分离技术,对企鹅珍珠贝闭壳肌、外套膜、鳃、消化盲囊、足组织的SOD、EST、LDH、G6PDH、MDH、ME 6种同工酶酶谱特征及其遗传控制进行了研究。6种同工酶在不同组织中的表达有明显的差异,同工酶分析共检测到18个位点,其中有16个位点具多态性,群体中,多态位点比例为88.8％,平均杂合度为0.396±0.029。有13个多态位点上的基因型频率与Hardy-Weinberg定律相符(P>0.05),位点Ldh-1、Ldh-2、Sod-2极显著偏离该平衡(P<0.01)

Single-sensor maximum power point tracking algorithms

Single-sensor maximum power point tracking algorithms for photovoltaic systems are presented. The algorithms have the features, characteristics and advantages of the widely used incremental conductance (INC) algorithm. However; unlike the INC algorithm which requires two sensors (the voltage sensor and the current sensor), the single-sensor algorithms are more desirable because they require only one sensor: the voltage sensor. The algorithms operate by maximising power at the DC-DC converter output, instead of the input. © 2013 The Institution of Engineering and Technology.

不同湖泊演替过程中浮游动物数量及多样性的研究

作者对长江中下游的湖北省保安湖的扁担塘、桥墩湖区、青菱湖的有草区（称南青菱湖）和无草区（称北青菱湖）及黄家湖等五个湖泊（区）浮游动物的种类组成、密度、多样性进行了研究。扁担塘常见浮游动物104种，桥墩湖107种，南青菱湖89种，北青菱湖73种，黄家湖88种，浮游动物的种类均随着水草生物量的减少而下降。浮游动物的密度均随着水草生物量的减少而增多。上述湖泊（区）浮游动物无论是种类组成还是密度均以小型的原生动物和轮虫占绝对优势。浮游动物多样性指数的变化与水草的丰度密切相关。随着湖泊水草生物量的增加，浮游动物的多

Static and dynamic errors in particle tracking microrheology.

Particle tracking techniques are often used to assess the local mechanical properties of cells and biological fluids. The extracted trajectories are exploited to compute the mean-squared displacement that characterizes the dynamics of the probe particles. Limited spatial resolution and statistical uncertainty are the limiting factors that alter the accuracy of the mean-squared displacement estimation. We precisely quantified the effect of localization errors in the determination of the mean-squared displacement by separating the sources of these errors into two separate contributions. A "static error" arises in the position measurements of immobilized particles. A "dynamic error" comes from the particle motion during the finite exposure time that is required for visualization. We calculated the propagation of these errors on the mean-squared displacement. We examined the impact of our error analysis on theoretical model fluids used in biorheology. These theoretical predictions were verified for purely viscous fluids using simulations and a multiple-particle tracking technique performed with video microscopy. We showed that the static contribution can be confidently corrected in dynamics studies by using static experiments performed at a similar noise-to-signal ratio. This groundwork allowed us to achieve higher resolution in the mean-squared displacement, and thus to increase the accuracy of microrheology studies.

富营养化浅水湖泊沉水水生植被的衰退与恢复

对国外近年来有关富营养化浅水湖泊的退化与恢复方面的研究进展以及生物操纵作用作了述评．对有关富营养化湖泊沉水植被衰退的有代表性的3种假说也作了介绍．根据“八五”期间武汉东湖水生植被重建的研究工作和多年积累的湖泊水生植被调查资料，提出了长江中下游浅湖富营养化过程中沉水植技演替的模式．

Product intelligence in industrial control: Theory and practice

This paper explores the evolving industrial control paradigm of product intelligence. The approach seeks to give a customer greater control over the processing of an order - by integrating technologies which allow for greater tracking of the order and methodologies which allow the customer [via the order] to dynamically influence the way the order is produced, stored or transported. The paper examines developments from four distinct perspectives: conceptual developments, theoretical issues, practical deployment and business opportunities. In each area, existing work is reviewed and open challenges for research are identified. The paper concludes by identifying four key obstacles to be overcome in order to successfully deploy product intelligence in an industrial application. © 2013 Elsevier Ltd. All rights reserved.

Dynamic compression of foam supported plates impacted by high velocity soil

The response of back-supported buffer plates comprising a solid face sheet and foam core backing impacted by a column of high velocity particles (sand slug) is investigated via a lumped parameter model and coupled discrete/continuum simulations. The buffer plate is either resting on (unattached) or attached to a rigid stationary foundation. The lumped parameter model is used to construct maps of the regimes of behaviour with axes of the ratio of the height of the sand slug to core thickness and the normalised core strength. Four regimes of behaviour are identified based on whether the core compression ends prior to the densification of the sand slug or vice versa. Coupled discrete/continuum simulations are also reported and compared with the lumped parameter model. While the model predicted regimes of behaviour are in excellent agreement with numerical simulations, the lumped parameter model is unable to predict the momentum transmitted to the supports as it neglects the role of elasticity in both the buffer plate and the sand slug. The numerical calculations show that the momentum transfer is minimised for intermediate values of the core strength when the so-called "soft-catch" mechanism is in play. In this regime the bounce-back of the sand slug is minimised which reduces the momentum transfer. However, in this regime, the impulse reduction is small (less than 10% of that transferred to a rigid structure). For high values of the core strength, the response of the buffer plate resembles a rigid plate with nearly no impulse mitigation while at low values of core strength, a slap event occurs when the face sheet impinges against the foundation due to full densification of the foam core. This slap event results in a significant enhancement of the momentum transfer to the foundation. The results demonstrate that appropriately designed buffer plates have potential as impulse mitigators in landmine loading situations. © 2013 Elsevier Ltd. All rights reserved.

固定化假单胞菌CTP-01细胞分解对硫磷的研究

用明胶-戊二醛(GGA)和聚丙烯酰胺(PAA)包埋的固定化Pseudomonas sp.CTP-01细胞具有降解对硫磷的特性。GGA固定化细胞水解对硫磷的活力比PAA固定化细胞高5.8倍。当保存在4℃时GGA和PAA固定化细胞分别可以保持活力31.3和70%。GGA和PAA包埋的细胞最适反应温度分别为50℃到70℃和60℃到70℃,然而整细胞在温度超过65℃时活力很快下降。GGA和PAA两种固定化细胞最适pH为8.0,当pH低于7.0时活力开始下降,pH4吋则完全失活。