Seismic damage detection for a steel braced frame structure

A new approach for global detection of seismic damage in a single-storey steel concentrically braced frame (CBF) structure is presented. The filtered lateral in-plane acceleration response of the CBF structure is integrated twice to provide the lateral in-plane displacement which is used to infer buckling and yielding damage. The level of interstorey drift of the CBF during a seismic excitation allows the yield and buckling of the bracing members to be identified and indirectly detects damage based on exceedance of calculated lateral in-plane displacement limits. A band-pass filter removes noise from the acceleration signal followed by baseline correction being used to reduce the drift in velocity and displacement during numerical integration. This pre-processing results in reliable numerical integration of the frame acceleration that predicts the displacement response accurately when compared to the measured lateral displacement of the CBF structure. Importantly, the structural damage is not assumed through removal of bracing members, rather damage is induced through actual seismic loading. The buckling and yielding displacement threshold limits used to identify damage are demonstrated to accurately identify the initiation of buckling and yielding.

On the Limits of Exceptionalism: Principles and Practice in the Pursuit of Alternatives to Full EU Membership

Few states have been less uncomfortable with the relationship they have with the EU than the United Kingdom as a member and Turkey as an associate and would-be member. Both states currently find themselves questioning the substance and future of these relationships with domestic actors and, notably in the Turkish case, external EU voices actively advocating alternatives. While much discussion, particularly in the UK case, has focused on the advantages and disadvantages of particular existing arrangements (e.g. European Economic Area, Swiss bilateralism), this paper considers the broader principles and practices that the EU has to date either explicitly developed or implicitly established to govern the nature and substance of alternatives to [full] EU membership. It assesses the principled, practical and political limitations that exist in establishing alternatives to full membership for states seeking – or having sought for them – the accommodation of their exceptionalism. In doing so the paper considers the potential limits to a renegotiated EU membership for the UK and to an alternative short of full membership for Turkey. It also reflects on the precedent-setting consequences of any new arrangements that the EU might reach with either state for what forms membership and a relationship short of membership might take in the future.

Wing Panel Design with Novel Skin-Buckling Containment Features

The impact of buckling containment features on the stability of thin-gauge fuselage, metallic stiffened panels has previously been demonstrated. With the continuing developments in manufacturing technology, such as welding, extrusion, machining, and additive layer manufacture, understanding the benefits of additional panel design features on heavier applications, such as wing panels, is timely. This compression testing of thick-gauge panels with and without buckling containment features has been undertaken to verify buckling and collapse behaviors and validate sizing methods. The experimental results demonstrated individual panel mass savings on the order of 9%, and wing cover design studies demonstrated mass savings on the order of 4 to 13%, dependent on aircraft size and material choice.

Performance Limits of MIMO Systems with Nonlinear Power Amplifiers

The development of 5G enabling technologies brings new challenges to the design of power amplifiers (PAs). In particular, there is a strong demand for low-cost, nonlinear PAs which, however, introduce nonlinear distortions. On the other hand, contemporary expensive PAs show great power efficiency in their nonlinear region. Inspired by this trade-off between nonlinearity distortions and efficiency, finding an optimal operating point is highly desirable. Hence, it is first necessary to fully understand how and how much the performance of multiple-input multiple-output (MIMO) systems deteriorates with PA nonlinearities. In this paper, we first reduce the ergodic achievable rate (EAR) optimization from a power allocation to a power control problem with only one optimization variable, i.e. total input power. Then, we develop a closed-form expression for the EAR, where this variable is fixed. Since this expression is intractable for further analysis, two simple lower bounds and one upper bound are proposed. These bounds enable us to find the best input power and approach the channel capacity. Finally, our simulation results evaluate the EAR of MIMO channels in the presence of nonlinearities. An important observation is that the MIMO performance can be significantly degraded if we utilize the whole power budget.

European Union Cross-Border Cooperation as Conflict Transformation:Potential and Limits

Cross-border cooperation as conflict transformation provides a potential strategy for the European Union (EU) to help realise its founding peacebuilding objective. A wealth of cross-border cooperation activity sponsored by the EU spans a quarter of a century. Although the conflict transformation capacity of that cooperation is questionable in some border regions there is evidence to suggest that it has delivered peacebuilding dividends in other border regions. However, EU cross-border cooperation as conflict transformation faces a number of significant twenty-first century challenges including: ghost borders of the communal imagination; EU external border securitization; perceptions of EU and Russian empire-building; and the Mediterranean transmigrant/refugee crisis. It is argued that these challenges pose significant obstacles to EU cross-border cooperation as conflict transformation and undermine the peacebuilding objective of European integration.

Economic Stability and Economic Governance in the Euro Area:What the European Crisis Can Teach on the Limits of Economic Integration

The recent European economic crisis has dramatically exposed the failures of
the various institutional mechanisms in place to maintain economic stability
in Europe, and has unveiled the difficulty in achieving international coordination
on fiscal and financial stability policies. Drawing on the European
experience, this article analyzes the concept of economic stability in international
law and highlights the peculiar problems connected to its maintenance
or promotion. First, we demonstrate that policies that safeguard and
protect economic stability are largely regulated and managed at the national
level, due to their inextricable relationship with the exercise of national political
power. Until recently, more limited levels of pan-European integration
did not make the coordination of economic stability policies seem necessary.
However, a much deeper level of economic integration makes it very difficult
to tackle an international economic crisis through national responses. If EU
Member states wish to maintain and deepen economic integration, they
must accept an erosion of sovereignty over their economic stability policies.
This will not only deprive states of a fundamental anchor of political power,
but also create a challenge for the maintenance of democratic control over
economic policies. Second, this article argues that soft law approaches are
likely ineffective in enforcing the regulatory disciplines required to ensure
economic stability.

ORBS and the limits of static slicing

Observation-based slicing is a recently-introduced, language-independent, slicing technique based on the dependencies observable from program behaviour. Due to the wellknown limits of dynamic analysis, we may only compute an under-approximation of the true observation-based slice. However, because the observation-based slice captures all possible dependence that can be observed, even such approximations can yield insight into the limitations of static slicing. For example, a static slice, S that is strictly smaller than the corresponding observation based slice is guaranteed to be unsafe. We present the results of three sets of experiments on 12 different programs, including benchmarks and larger programs, which investigate the relationship between static and observation-based slicing. We show that, in extreme cases, observation-based slices can find the true static minimal slice, where static techniques cannot. For more typical cases, our results illustrate the potential for observation-based slicing to highlight unsafe static slices. Finally, we report on the sensitivity of observation-based slicing to test quality.

Aggregation Limits Surface Expression of Homomeric GluA3 Receptors

AMPA receptors are glutamate-gated cation channels assembled from GluA1-4 subunits and have properties that are strongly dependent on the subunit composition. The subunits have different propensities to form homomeric or various heteromeric receptors expressed on cell surface, but the underlying mechanisms are still poorly understood. Here, we examined the biochemical basis for the poor ability of GluA3 subunits to form homomeric receptors, linked previously to two amino acid residues, Y454 and R461, in its ligand-binding domain (LBD). Surface expression of GluA3 was improved by co-assembly with GluA2 but not with stargazin, a trafficking chaperone and modulator of AMPA receptors. The secretion efficiency of GluA2 and GluA3 LBDs paralleled the transport difference between the respective full-length receptors and was similarly dependent on Y454/R461, but not on LBD stability. In comparison to GluA2, GluA3 homomeric receptors showed a strong and Y454/R461-dependent tendency to aggregate both in the macroscopic scale measured as lower solubility in nonionic detergent and in the microscopic scale evident as the preponderance of hydrodynamically large structures in density gradient centrifugation and native gel electrophoresis. We conclude that the impaired surface expression of homomeric GluA3 receptors is caused by nonproductive assembly and aggregation to which LBD residues Y454 and R461 strongly contribute. This aggregation inhibits the entry of newly synthesized GluA3 receptors to the secretory pathway.

Buckling strength of adhesively-bonded single and double-strap repairs on carbon-epoxy structures

This work reports on an experimental and finite element method (FEM) parametric study of adhesively-bonded single and double-strap repairs on carbon-epoxy structures under buckling unrestrained compression. The influence of the overlap length and patch thickness was evaluated. This loading gains a particular significance from the additional characteristic mechanisms of structures under compression, such as fibres microbuckling, for buckling restrained structures, or global buckling of the assembly, if no transverse restriction exists. The FEM analysis is based on the use of cohesive elements including mixed-mode criteria to simulate a cohesive fracture of the adhesive layer. Trapezoidal laws in pure modes I and II were used to account for the ductility of most structural adhesives. These laws were estimated for the adhesive used from double cantilever beam (DCB) and end-notched flexure (ENF) tests, respectively, using an inverse technique. The pure mode III cohesive law was equalled to the pure mode II one. Compression failure in the laminates was predicted using a stress-based criterion. The accurate FEM predictions open a good prospect for the reduction of the extensive experimentation in the design of carbon-epoxy repairs. Design principles were also established for these repairs under buckling.

New and low cost plastic membrane electrode with low detection limits for sulfadimethoxine determination in aquaculture waters

Sulfadimethoxine (SDM) is one of the drugs, often used in the aquaculture sector to prevent the spread of disease in freshwater fish aquaculture. Its spread through the soil and surface water can contribute to an increase in bacterial resistance. It is therefore important to control this product in the environment. This work proposes a simple and low-cost potentiometric device to monitor the levels of SDM in aquaculture waters, thus avoiding its unnecessary release throughout the environment. The device combines a micropipette tip with a PVC membrane selective to SDM, prepared from an appropriate cocktail, and an inner reference solution. The membrane includes 1% of a porphyrin derivative acting as ionophore and a small amount of a lipophilic cationic additive (corresponding to 0.2% in molar ratio). The composition of the inner solution was optimized with regard to the kind and/or concentration of primary ion, chelating agent and/or a specific interfering charged species, in different concentration ranges. Electrodes constructed with inner reference solutions of 1 × 10−8 mol/L SDM and 1 × 10−4 mol/L chromate ion showed the best analytical features. Near-Nernstian response was obtained with slopes of −54.1 mV/decade, an extraordinary detection limit of 7.5 ng/mL (2.4 × 10−8 mol/L) when compared with other electrodes of the same type. The reproducibility, stability and response time are good and even better than those obtained by liquid contact ISEs. Recovery values of 98.9% were obtained from the analysis of aquaculture water samples.