The damped cable system for seismic protection of frame structures — Part II: Design and application

The complementary sections of the studies carried out on the damped cable system, whose experimental and numerical characterization and assessment analyses are described in the companion paper, are presented herein. The first section includes a criterion for a preliminary evaluation of the section area of cables, the second branch stiffness of spring‐dampers and the mutual installation preload, and suggestions for a simplified nonlinear dynamic computation of the damping coefficient of dissipaters. A second section follows, aimed at evaluating the influence of cable layout on damped cable system performance. A numerical enquiry is developed on a four‐story and an eight‐story RC plane frame, to assess their seismic response for several shapes of cables, and determine what geometrical configurations are the best performing ones. In the third section, a demonstrative application of the protective system, represented by the seismic retrofit of a hospital building with RC structure, is offered. The characteristics of the system designed for this case study, including locations, dimensions, layouts, and technical installation details of cables and spring‐dampers, are illustrated, and the improvement of seismic performance as compared with the original conditions, is finally assessed. Copyright © 2011 John Wiley & Sons, Ltd.     

Three-dimensional hydrodynamical simulations of the large-scale structure of W50−SS433

We present 3D hydrodynamical simulations of a precessing jet propagating inside a supernova remnant (SNR) shell, particularly applied to the W50−SS433 system in a search for the origin of its peculiar elongated morphology. Several runs were carried out with different values for the mass-loss rate of the jet, the initial radius of the SNR, and the opening angle of the precession cone. We found that our models successfully reproduce the scale and morphology of W50 when the opening angle of the jets is set to 10° or if this angle linearly varies with time. For these models, more realistic runs were made considering that the remnant is expanding into an interstellar medium with an exponential density profile (as H  i observations suggest). Taking into account all these ingredients, the large-scale morphology of the W50−SS433 system, including the asymmetry between the lobes (formed by the jet–SNR interaction), is well reproduced.     

Antioxidants in the black mussel (Mytilus galloprovincialis) as an indicator of Black Sea coastal pollution

The biologically active compounds, antioxidant activities, and free radical scavenging effects of black mussel dry matter (Mytilus galloprovincialis)--(BMDM) were investigated. The extract from BMDM with absolute methanol (BMDMAMet) showed the strongest inhibition of lipid peroxidation as a function of its concentration, and was comparable to the antioxidant activity of butylated hydroxyanisole, at the same concentration of 0.2 mg/ml. The extract with 50%methanol/water (BMDM50%Met) had the weakest antioxidant activity, whereas other extracts such as 1.2 M HCl in 50%methanol/water (BMDM50%Met/HCl) exhibited an average inhibition of lipid peroxidation. BMDMAMet extract showed marked activities in free radical scavenging determined by beta-carotene bleaching (beta-carotene), nitric oxide (NO*) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) radical cation (ABTS*+ methods. The antioxidant activities of BMDMAMet extract determined beta-carotene, NO* and ABTS*+ methods showed the highest correlation coefficients (R2) such as 0.998, 0.9976 and 0.6103, respectively, with the presence of total polyphenols. BMDM50%Met had lower antioxidant ability than BMDM50%Met/HCl in different scavenging methods, indicating that the major antioxidant components in these extracts must be derived from the polyphenols. Correlation between proteins and antioxidants was very low (0.0318 and 0.0433). The mussel extracts from polluted areas have shown by all using methods higher antioxidant activity than from the clean ones. The results presented in this report indicate that the antioxidant activities of mussel extracts could possibly be an additional index of pollution characterization.     

Wave propagation along freely propagating surface gravity current fronts

This work deals with the propagation and evolution of disturbances which move along freely propagating two-dimensional gravity current fronts. Examples of evolving perturbations on fronts are displayed in real-aperture radar images of gravity currents in the coastal zone. The theory of Cooper et al. (2001), which is based upon the ray tube formulation of Whitham (1974), is employed to simulate disturbances of the sort seen in this imagery and in the larger body of literature. Initial anomalies in both shape and velocity are introduced and allowed to evolve, and several types of new and interesting behaviors emerge. Shape perturbations of the form x=a sech δy evolve into two anomalies, which separate in time as they propagate in opposite directions along the front. When the value of a is increased, the disturbances, which propagate along the gravity current, can break, forming breaking frontal waves (BFWs). These manifest themselves as sharp angular features to either side of the main bulge. Two types of velocity disturbances are employed. The first has the form U=U₀(1+â sech δy), and evolves to preserve a single frontal bulge that increases in amplitude and width as it propagates. Here again, large values of â result in BFWs. In this case, they replicate the general behavior present in the imagery. The second type of velocity perturbation used is U=U₀(1+â cos δy). The smallest values of a generate no BFWs, but yield fronts which oscillate in space and time. Larger values produce a string of BFWs which are qualitatively similar to the cusp-and-trough morphology observed so frequently in nature. The largest values of a allow the gravity current to form a string of large, bulbous structures which intersect one another as they propagate forward and spread laterally. And finally, we make an effort to correlate the results of the simulations with the shapes seen in radar and visible imagery in the literature.     

Distribution of copper, zinc, lead and cadmium concentrations in stream sediments from the Mapocho River in Santiago, Chile

The Mapocho river, which crosses downtown Santiago, is one of the most important rivers in contact with a population of about six million inhabitants. Anthropogenic activities, industrialization, farming activities, transport, urbanization, animal and human excretions, domestic wastes and copper mining have affected the river, contaminating it and its sediments with heavy metals. Concentration and distribution of Cu, Zn, Pb and Cd were studied with the purpose of determining their bioavailability and their relation with the characteristics of the sediments. Freshly deposited seasonal sediments were collected from 0–8 cm depths from 6 locations (S₁ to S₆) along the 30-km long channel length, in the four seasons of year on the following dates: May 2001 (D₁, autumn); August 2001 (D₂, winter); October 2001 (D₃, spring) and January 2002 (D₄, summer). The dried samples were sifted to obtain the < 63-μm sediment fraction, since it has been shown that large amounts of heavy metals are bound in the fine-grained fraction of the sediment. Cu and Zn were analyzed by atomic absorption spectrophotometry and Pb and Cd by square wave anodic stripping voltammetry. The highest concentrations of Cu (2850 μg g^− 1) were found in the northern part of the river (S₁, average D₁–D₄), near the mountains and a copper mine, and then decreased downstream to 209 μg g^− 1 (S₆). Total Zn showed an irregular variation, with higher values at S₁ (1290 μg g^− 1) and high values in some winter sampling (1384 μg g^− 1 S₄, S₅–D₂). Pb showed different trends, increasing from S₁ to S₆ (17 to 61 μg g^− 1), with the highest values in the summer samples (83 μg g^− 1, S₄–S₆, D₄), and total Cd increased slightly from mean values of 0.2 and 0.5 μg g^− 1. Partition into five fractions was made using Tessier's analytical sequential extraction technique; the residue was treated with aqua regia for recovery studies, although this step is not part of the Tessier procedure. The results show that Cu, Zn and Pb in the sediments were dependent on the sampling places along the river, and variation in two years was low (D₁–D₄). The highest values of total organic matter, carbonate and conductivity were found in S₆, which has the smallest size particles, while at S₁ the sediments were predominantly sand and contain larger amounts of silica. Cu associated with carbonate decreased gradually from 58% (1771 μg g^− 1, S₁) to 16% (32 μg g^− 1, S₆); Cu bonded to reducible fraction was almost constant (33% to 37%), and Cu associated with oxidizable fraction increased from 7% (S₁) to 34% (S₆), but copper content was lower (214 to 68 μg g^− 1). Zn had a similar fractionation profile. However, Pb bound to oxidizable fraction did not show significant percent variation along the river (20% to 19%), but the amount bounded was 4 to 12 μg g^− 1. The residual fraction increased from 24% to 41% (5 to 25 μg g^− 1, S₁ to S₆). The distribution of Cd in the sediment was almost independent of the sampling stations and was bound to carbonate, reducible and residual fraction in similar proportion. Cu and Zn at S₁ were mainly bound to carbonates and reducible phases with 91% and 73% (2779 and 965 μg g^− 1, respectively), and with a change in the pH and/or the redox potential of the sediment–water system, these contaminants could easily enter the food chain. In S₆ the amount of Cu and Zn in these phases was 50% and 53% (100 to 313 μg g^− 1, respectively).     

A cross-analysis framework for multi-source volunteered,crowdsourced, and authoritative geographic information: The case study of volunteered personal traces analysis against transport network data

Abstract

The paper discusses the need of a high-level query language to allow analysts, geographers and, in general, non-programmers to easily cross-analyze multi-source VGI created by means of apps, crowd-sourced data from social networks and authoritative geo-referenced data, usually represented as JSON data sets (nowadays, the de facto standard for data exported by social networks). Since an easy to use high-level language for querying and manipulating collections of possibly geo-tagged JSON objects is still unavailable, we propose a truly declarative language, named J-CO-QL, that is based on a well-defined execution model. A plug-in for a GIS permits to visualize geo-tagged data sets stored in a NoSQL database such as MongoDB; furthermore, the same plug-in can be used to write and execute J-CO-QL queries on those databases. The paper introduces the language by exemplifying its operators within a real study case, the aim of which is to understand the mobility of people in the neighborhood of Bergamo city. Cross-analysis of data about transportation networks and VGI from travelers is performed, by means of J-CO-QL language, capable to manipulate and transform, combine and join possibly geo-tagged JSON objects, in order to produce new possibly geo-tagged JSON objects satisfying users’ needs.     

Competition Between Littoral Cladocerans Macrothrix triserialis and Alona rectangula (Cladocera) in Relation to Algal Food Level and Inoculation Density

We studied the relative competitive abilities of littoral cladocerans M.triserialis and A. rectangula using green algal food at two levels (0.5 · 10⁶ and 2 · 10⁶ cells mL⁻¹ of Chlorella) under five different inoculation ratios. Both the cladoceran species were influenced by food availability and mutual competitive pressure. Macrothrix could withstand competition better under conditions of lower food availability while Alona grew better, despite competition, when more Chlorella was available. Population growth rates (r) ranged from 0.022…0.070 for Alona and from 0.024…0.075 for Macrothrix. There was a significant impact of the inoculation ratio on the maximal population density reached by either test species. Food concentration had a significant influence on the peak population density reached only for Alona rectangula. Data on the body sizes of M. triserialis and A. rectangula showed that there was a higher somatic growth with increasing food availability and decreased competitive pressure in both the test species. In Macrothrix, food concentration and the competition from Alona through different initial inoculation densities had a significant impact on the body size. At the lower food concentration, the body size was significantly smaller when the inoculation density was lowest (highest competitive pressure). The body size of Alona, on the other hand, was not affected by the competition but was significantly higher under conditions of greater food availability. These results have been discussed in light of different theories of competition.     

Relative importance of dust inputs and aquatic biological production as sources of lake sediments in an oligotrophic lake in a semi‐arid area

The dustfall (DF) and mass sedimentation rate (MSR) in Lake Alchichica, Central Mexico, were studied from June 2006 to June 2008. DF ranged between 0·11–0·93 g m^?2 d^?1 in the warm and rainy season and 0·54–1·21 g m^?2 d^?1 in the cold and dry season. MSR varied from 0·52–2·40 g m^?2 d^?1 in the stratification season to 1·14–5·07 g m^?2 d^?1 in the circulation season. The timing of the highest fluxes of DF and MSR is most likely a product of several factors coinciding during the cold and dry season: (a) availability of dust sources and the presence of strong winds (>7·5 m s^?1) in the DF case, and (b) the circulation period of the lake and the availability of nutrients in the MSR case. As expected, the DF in Alchichica was high and similar to that found in other arid and semi‐arid areas. However, the MSR was higher than that reported for other oligotrophic lakes. Particles captured in the aerial traps consisted mainly of detrital minerals; in contrast, particles found in the water traps were mostly biogenic and, to a lesser extent, detrital minerals. The MSR was one to seven times higher than the DF. In spite of the oligotrophic status of Lake Alchichica, the large size of the settled phytoplankton (autochthonous, waterborne) is what leads to the high MSR, which surpasses the DF (allochthonous, airborne) derived from whirlwinds originating in easily eroded terrains that are characteristic of arid/semi‐arid areas. Our results indicate that caution must be taken in considering that the DF amount measured through DF collectors located at the lake shore does actually represent the DF entering into the lake. Copyright © 2010 John Wiley & Sons, Ltd.