Full Height Research Articles

Precision of fit and retention force of cast non-precious-crowns on standard titanium implant-abutment with different design and height

The cost-effectiveness of cast nonprecious frameworks has increased their prevalence in cemented implant crowns. The purpose of this study was to assess the effect of the design and height of the retentive component of a standard titanium implant abutment on the fit, possible horizontal rotation and retention forces of cast nonprecious alloy crowns prior to cementation. Two abutment designs were examined: Type A with a 6° taper and 8 antirotation planes (Straumann Tissue-Level RN) and Type B with a 7.5° taper and 1 antirotation plane (SICace implant). Both types were analyzed using 60 crowns: 20 with a full abutment height (6mm), 20 with a medium abutment height (4mm), and 20 with a minimal (2.5mm) abutment height. The marginal and internal fit and the degree of possible rotation were evaluated by using polyvinylsiloxane impressions under a light microscope (magnification of ×50). To measure the retention force, a custom force-measuring device was employed. one-sided Wilcoxon rank-sum tests with Bonferroni-Holm corrections, Fisher's exact tests, and Spearman's rank correlation coefficient. Type A exhibited increased marginal gaps (primary end-point: 55±20μm vs. 138±59μm, P<0.001) but less rotation (P<0.001) than Type B. The internal fit was also better for Type A than for Type B (P<0.001). The retention force of Type A (2.49±3.2N) was higher (P=0.019) than that of Type B (1.27±0.84N). Reduction in abutment height did not affect the variables observed. Less-tapered abutments with more antirotation planes provide an increase in the retention force, which confines the horizontal rotation but widens the marginal gaps of the crowns. Thus, casting of nonprecious crowns with Type A abutments may result in clinically unfavorable marginal gaps.

Gas emissions as influenced by home composting system configuration

Home composting systems (HC) are known to facilitate municipal solid waste management, but little is known about their environmental impact including their greenhouse gas emissions (GGE). The present research focused on selecting HC configuration producing the least CH4 and N2O. Thus, 4 HC types were used to compost food and yard waste for 150 days and monitored for CO2, CH4 and N2O as of day 15: the wood and plastic bins (WB and PB), the mixed and unmixed ground pile (GPM and GP). Using the same waste recipe, all HC were filled at once (batch fed) to maximize gaseous emissions. Weekly as of day 15, CO2, N2O and CH4 emissions were measured during 2-h sessions using a closed chamber inserted into the compost surface. Monitored compost characteristics indicated little differences over time except for moisture content. From day 15 to 150, CH4 emissions were not measurable. Generation of N2O occurred between day 20 and 120 with PB producing the least because of top and bottom slots providing continuous convective aeration, as compared to the WB with slats over its full height and the naturally aerated mixed and unmixed ground piles. Total N2O emissions of 56 kg CO2-eq (tonne wet waste treated)−1 for PB, 75 for GP, 97 for WB and 99 for GPM represented average value for centralized composting facilities. Present and past scientific works suggest the need for more research to establish the combined effect of management and HC configuration on gaseous emissions, with close CH4 measurements from day 0 to 15.

Role of Anatomical Implant in Augmentation of Glandular Ptotic Breast

Breast augmentation of ptotic micromastia is relatively difficult procedure than simple augmentation. Surgeon must make into account many variables, ptosis degree, chest wall size, shape, asymmetry, nipple and inframammary fold level, soft tissue characteristic etc. One-stage mastopexy augmentation procedure has higher patient acceptance because this limits the number of sick days and the need for hospital care, and it is also less expensive. Because of two procedures that has opposite effect to soft tissue be done in the same time, there can be high incidence of unfavorable outcomes and complications. Some well known doctors recommend that 2-step procedure of mastopexy folllowed by augmentation can be much better option. It can make more predictable result and it is also safe in soft tissue problem and vascularity. In one stage augmentation mastopexy, high and extrahigh projection implants have often been promoted for augmenting glandular ptotic breast, emphasizing the role of implant projection to the sagging parenchyma and skin of lower pole of breast anteriorly to "lift" the breast and "correct" the ptosis. High and extra high profile implants may contribute projection, but they are not the best choice for correction of glandular ptosis. It has several negatives, additional parenchymal atrophy, lower pole skin stretch and thinning and visible and palpable rippling. All of these tissue consequences are irreversible and uncorrectable. Optimal implant design for augmentation of glandular ptotic breast is full height, moderate profile, shaped, textured, form stable implant. Keywords: Breast implants, Silicone gels, Anatomical models, Mammoplasty

A qualitative investigation on double-skin façade fires

Fire hazard of the green architectural feature double-skin facade is always a concern. A hazard scenario with a room fire adjacent to the facade was identified earlier after interviewing with fire professionals. Experimental studies on the consequence of the fire hazard due to trapping heat and mass in the facade cavity carried out before will be reported in this presentation. The rig was of height 15 m with a fire chamber placed next to it. Flashover was induced to direct hot flame and smoke out. Only part of the building was studied instead of a full height facade due to resource limitations. Air temperature next to the upper interior glass pane was confirmed to be higher than the air temperature next to the exterior pane with normal air cavity depth in double-skin facades. Flame will then be diverted to the interior glass pane, giving possibility to spread fire to the upper rooms.

Trafficking: A Modern Scenario

Trafficking in persons is an increasing problem that involves both sexual exploitation and labour exploitation of its victims. Both men and women may be victims of trafficking, but the primary victims worldwide are women and girls, the majority of whom are trafficked for the purpose of sexual exploitation. Traffickers primarily target women because they are disproportionately affected by poverty and discrimination, factors that impede their access to employment, educational opportunities and other resources. Perhaps the strongest factor is a desperate economic situation, which impacts the availability of satisfactory employment in many countries for women. Traffickers prey on women's vulnerable circumstances and may lure them into crime networks through deceit and false promises of decent working conditions and fair pay. The majority of trafficked women find themselves trapped in debt bondage servitude or “slavery like” condition as a result of being trafficked. The problem of women has been addressed at the international, regional and national levels. Before the creation of the United Nations protocol to prevent, suppress and punish trafficking in persons, especially women and children in October 2000, international treaties refer to trafficking without defining or clarifying whether trafficking includes all form of sex work. Victims are always entitled to the protection of their basic human rights and any measures adopted to protect victims should take into account age, gender and any special needs. “It is a matter of bitter shame and sorrow and deep humiliation that a number of women have to sell their chastity for men's lust. Man, the law giver, will have to pay a dreadful penalty for the degradation he has imposed upon the so-called weaker sex. When woman freed from man's snares rises to the full height and rebels against man's legislation and institution designed by him, her rebellion, no doubt, non-violent, will be nevertheless effective” - Mahatma Gandhi.

A cross-correlation method for measuring line formation heights in the solar photosphere

Context. Detailed 3D-simulations of magneto-convection in the solar photosphere are now available. They intend to capture the main physical mechanisms at play in this boundary layer, where complex physical phenomena, such as convective overshooting and small scale magnetic dynamo take place. But numerical limitations in spatial resolution and in box-size are likely to affect the description of some relevant physical scales, so simulations need to be compared to independent observations allowing us to explore the full height range of the photosphere. Aims. Here we focus on a model-independent method for measuring line formation depths. We construct images of the photosphere at constant continuum opacity levels from the low to the upper photosphere and we show how they can be used to measure systematic displacements of granular structures with height. The method is applied to determine the formation height of the 630 nm Fe i line pair. We compare our measurements to the results of 3D simulations.Methods. We analyze high resolution spectroscopic scans obtained in the 630 nm Fe i line pair at varying heliocentric angles along the north-south polar axis of the Sun, with SOT onboard Hinode. We implement a new strategy for correcting the images observed at different line cords from spurious Doppler effects. The cross-correlations between continuum images and line core images show a clear anti-correlation peak due to the contrast inversion of the granulation in the upper photosphere, as predicted by magnetohydrodynamic (MHD) simulations.Results. The anti-correlation peak is shifted by the perspective effect and by horizontal velocity effects. Both effects may be distinguished because they have different center-to-limb variations. The measurement of the perspective shift allows us to determine the line core formation heights and their center-to-limb variations. The results are in good agreement with 3D- MHD simulations for images close to disk center, but close to the solar limb we measure larger formation heights than what is predicted by the simulations, which seem to fail in modeling properly the upper layers of the photosphere. As the granulation contrast inversion is observed at line centers, we can safely conclude that the height of the contrast inversion layer is smaller than 200 km.

Prediction of standing height among Israeli older adults: Results from a national survey

Background: An accurate measurement of full height while standing is sometimes not possible among older adults, in particular among the frail elderly. For such cases, the use of knee height (KH) and ulna bone length (UL) has been suggested for standing height estimation. Studies have shown that predictive equations of height were ethnic-specific.Aim: This study attempted to develop representative equations to predict standing height based on KH, UL and waist circumference (WC) for older adult Israeli women and men.Subjects and methods: A random sample of 1500 older adults (aged 74.48 ± 6.09 years old). Participants were interviewed in their homes and measurements of Standing height, KH, UL and WC were taken. A quadratic regression analysis, for each sex separately, was performed to predict standing height based on age, KH, UL and WC.Results: The adjusted r2 standing height prediction equations were 0.51 and 0.67 for women and men, respectively.Conclusions: The prediction of the standing height of frail elderly Israelis, by KH, UL, WC and age, may be an alternative method when actual standing height is difficult or not possible to measure.

Which macroarthropods prefer tree stumps over soil and litter substrates?

Tree stumps are a potential bioenergy resource to replace fossil fuels and meet the targets for reduced CO2 emissions. However, the effects of stump harvesting on wood-dependent organisms are poorly known. This study assessed the abundances of macroarthropods, especially non-coleopteran groups, in wood, bark and ‘periphery’ of stumps in comparison with soil to evaluate which species/taxa prefer stumps over soil and would risk a significant population decline following extensive stump harvesting. To assess the effects of stump age on species and individual numbers, 5-, 10- and 20-yr-old stumps were studied at three sites in southern and central Sweden. For each site and age class, stumps of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) were compared. Samples of wood and bark were taken from the full height of the stump and samples of periphery and soil to a depth of 10cm. The samples were placed in Tullgren funnels for animal extraction during 4days. A total of 56 species or other taxonomic groups not belonging to Coleoptera were identified. Bark (including the space between bark and wood) had significantly lower species richness of non-coleopteran macroarthropods but higher abundance per m2 (of cut stump surface) than soil in 10-yr-old stands, which on average contained higher abundances than the other age classes. No significant differences were found between spruce and pine stumps, indicating that one of the tree species can act as a substitute after stump harvesting of the other. Viewed over all substrates, Diplopoda, Coleoptera, Diptera (larvae) and Homoptera contributed most to the total abundance (29, 20, 17 and 15%, respectively). Of these groups, Diplopoda were much more abundant in bark (98%) than in soil (2%). The most common diplopod species was Proteroiulus fuscus, which often demonstrated 100-fold higher abundances (per sample unit) in bark and wood than in soil. Six species/taxa had clearly higher abundances in stumps than in soil. Stump harvesting would thus markedly reduce preferred habitats for these taxa. It is also possible that some species generally considered as soil animals might be occasionally dependent on stumps for, e.g. egg-laying and hatching. For such species, stump harvesting would be more detrimental than indicated by this population survey.

Enhancement of heat transfer in turbulent channel flow over dimpled surface

A systematic numerical investigation of heat transfer in turbulent channel flow over dimpled surface is conducted. Both symmetric (or spherical) and asymmetric dimple with different depth ratios (h/D) and skewness (Dx and Dz) are considered for a series of Reynolds numbers Re2H (based on bulk velocity and full channel height) between 4000 and 6000 while Prandtl number Pr is fixed at 0.7. It is found that the optimum dimple configuration for enhancing heat transfer measured in terms of the volume goodness factor is obtained for the case of asymmetric dimple with a depth ratio of h/D=15% and stream-wise skewness of Dx=15%. The heat transfer capacity in terms of Nusselt number is significantly increased, while the associated pressure loss is kept almost to the same level as the symmetric dimple with the same depth ratio. The present study also suggests that the heat transfer enhancement is closely related to ejection with counter-rotating flow, intensified secondary flow and vortex structures at the downstream rim of asymmetric dimple. All these findings suggest that a carefully designed asymmetric dimpled surface presents a viable means of enhancing heat transfer compared to the symmetric dimple.

Analytical simulation of reversed cyclic lateral behaviors of an RC shear wall sub-assemblage

Experimental results of cyclic reversed lateral force test on a two-story reinforced concrete shear wall sub-assemblage are simulated analytically by using the PERFORM-3D program. A comparison of experimental and analytical results leads to the following conclusions: (1) "Shear Wall" and "General Wall" models with "Concrete shear" cannot simulate the pinching phenomena due to shear and show larger amounts of inelastic energy absorption than those in the experiment. (2) Modeling a story-height wall by using two or more "General Wall" elements with "Diagonal shear" in the vertical direction induces the phenomenon of swelling-out at the belly, leading to the erroneous simulation of shear behaviors. In application to tall building structures, it is recommended to use one element of "General Wall" with "Diagonal shear" for the full height of a story. (3) In the plastic hinge area, concrete deformations of analytical models overestimate elongation and underestimate shortening when compared with experimental results.

Uncovering the molecular assembly of metal–organic frameworks through scanning force microscopy

Understanding the fundamental aspects of the crystal growth of metal organic frameworks (MOFs) is critical to develop better materials for new and enhanced applications. Some of the most pressing questions in this regard are the formation of the structure around the voids in the framework or the factors that control the morphology of the crystals. Only direct observations at the nanoscale under growing conditions can reveal the answers to these fundamental questions. Atomic forcemicroscopy (AFM) can provide these kind of detailed observations. In this paper we report results from in-situ AFM growth experiments for three different MOFs: MOF-5, ZIF-8 and ZIF-76. AFM images of the three types of crystals growing under low supersaturation conditions reveal similar results. In all cases growth was observed to take place by a birth and spread and/or spiral growth mechanism. Detailed height analysis of 2-D nuclei as a function of lateral spreading revealed a complexmechanism of terrace growth for all three systems. For ZIF-76 five different heights were measured: 0.6, 1.0, 1.4, 1.8 and 2.3 nm. The last height is equal to that of a full monolayer height or d100 spacing, which corresponds to a double four ring (D4R) plus a sodalite (SOD) cage of the LTA-type structure of ZIF-76. The other heights correspond to the height of single D4R (0.6 nm) or the sum of a D4R plus an incomplete SOD cage. For ZIF-8, a similar stepwise building process was observed with heights corresponding to the addition of Zn ions or methylimidazole linkers to complete the constituent sodalite cages that provide the step stable termination. In the case of MOF-5 only two heights were measured during 2-D nucleation and growth, corresponding to addition of the Zn clusters and benzendicarboxylic (bdc) linker. These measurements indicate that MOF crystal growth takes place by the nucleation and spreading of successive metastable unenclosed sub-layers to eventually form the stable, enclosed framework structure. This process is dependent on the presence of non-framework species that bridge the developing pores during growth. During the experiments on MOF-5, it was also observed that varying the stoichiometry of theMOF-5 growing solutions resulted in a dramatic change in terrace morphology. Solutions with a Zn/H2bdc ratio > 1 produced square terraces with steps parallel to the d directions. However, if the Zn/H2bdc ratio is approximately one, the steps become parallel to the o direction, resulting in a rhomboid terrace morphology. Additionally, a change in MOF-5 crystal shape was observed from the pure cubic morphology to blunted cubes and octahedra expressing the {111} facets indicating a change in the relative growth rates of the different faces that define the crystal morphology. These results provide a modulator-free route to control the crystal morphology of MOF-5 and potentially other MOFs. MS44-O2 In situ observations of impurity effects during protein crystallization. Mike Sleutel, Dominique Maes, Structural Biology Brussels, Flanders Interuniversity Institute for Biotechnology (VIB), Vrije Universiteit Brussel, Pleinlaan 2, 1050, Elsene, Belgium E-mail: mike.sleutel@vub.ac.be

Micrometer-scale synchrotron diffraction mapping analysis of carbide precipitation in deep cryogenically treated low carbon steel

Abstract

Surface Phase Diagram of 4H-SiC {0001} Step-Terrace Structures during Si-Vapor Etching in a TaC Crucible

Step-terrace structures were observed at on-axis/4o off 4H-SiC {0001} surfaces after Si-vapor etching which we have been supposed as an original technique to planarize and etch the SiC surfaces by utilizing a TaC crucible in temperature ranged from 1600 to 2200 oC. The structures obtained after the Si-vapor etching obviously indicated temperature dependence. There were two types of step-terrace structures in terms of the step height and the shape of the step edges at on-axis surfaces. Step bunched surfaces consisting of full unit cell height (= 1.0 nm) steps with {1-10n} facets at the step edges were observed at 4H-SiC (0001) in lower temperatures below 2000 oC, while smooth isotropic surfaces with half unit cell height (= 0.5 nm) steps and without any stable facets at the step edges were observed at 4H-SiC (0001) in higher temperatures above 2000 oC and in all temperature conditions (1600 - 2200 oC) at 4H-SiC (000-1). Similar tendency was also confirmed at 4o off 4H-SiC {0001} surfaces. From the comparison with 6H-SiC, macro step bunching (~10 nm height) was revealed to be a unique phenomenon at 4H-SiC (0001) surface in the etching.

Turbulent buoyant convection from a maintained source of buoyancy in a narrow vertical tank

AbstractWe describe new experiments to examine the buoyancy-induced mixing which results from the injection of a small constant volume flux of fluid of density ${\rho }_{s} $ at the top of a long narrow vertical tank with square cross-section which is filled with fluid of density ${\rho }_{0} \lt {\rho }_{s} $. The injected fluid vigorously mixes with the less dense fluid which initially occupies the tank, such that a dense mixed region of turbulent fluid propagates downwards during the initial mixing phase of the experiment. For an ideal source of constant buoyancy flux ${B}_{s} $, we show that the height of the mixed region grows as $h\ensuremath{\sim} { B}_{s}^{1/ 6} {d}^{1/ 3} {t}^{1/ 2} $ and that the horizontally averaged reduced gravity $ \overline{{g}^{\ensuremath{\prime} } } = g( \overline{\rho } \ensuremath{-} {\rho }_{0} )/ {\rho }_{0} $ at the top of tank increases as $ \overline{{g}^{\ensuremath{\prime} } } (0)\ensuremath{\sim} { B}_{s}^{5/ 6} {d}^{\ensuremath{-} 7/ 3} {t}^{1/ 2} $, where $d$ is the width of the tank. Once the mixed region reaches the bottom of the tank, the turbulent mixing continues in an intermediate mixing phase, and we demonstrate that the reduced gravity at each height increases approximately linearly with time. This suggests that the buoyancy flux is uniformly distributed over the full height of the tank. The overall density gradient between the top and bottom of the mixed region is hence time-independent for both the mixing phases before and after the mixed region has reached the bottom of the tank. Our results are consistent with previous models developed for the mixing of an unstable density gradient in a confined geometry, based on Prandtl’s mixing length theory, which suggest that the turbulent diffusion coefficient and the magnitude of the local turbulent flux are given by the nonlinear relations ${ \kappa }_{T}^{\mathit{nl}} = {\lambda }^{2} {d}^{2} \mathop{ (\partial \overline{{g}^{\ensuremath{\prime} } } / \partial z)}\nolimits ^{1/ 2} $ and ${J}^{\mathit{nl}} = {\lambda }^{2} {d}^{2} \mathop{ (\partial \overline{{g}^{\ensuremath{\prime} } } / \partial z)}\nolimits ^{3/ 2} $, respectively. The $O(1)$ constant $\lambda $ relates the width of the tank to the characteristic mixing length of the turbulent eddies. Since the mixed region is characterized by a time-independent overall density gradient, we also tested the predictions based on a linear model in which the turbulent diffusion coefficient is approximated by a constant ${ \kappa }_{T}^{l} $. We solve the corresponding nonlinear and linear turbulent diffusion equations for both mixing phases, and show a good agreement with experimental profiles measured by a dye attenuation technique, in particular for the solutions based on the nonlinear model.

Cold flow model investigations of the countercurrent flow of a dual circulating fluidized bed gasifier

A novel fluidized bed gasification concept with enhanced gas–particle interaction combining two circulating fluidized bed reactors is proposed. Cold flow model results show the feasibility of the concept with regard to fluid dynamics. The aim of the design is to generate a nitrogen (N2) free product gas with low tars and fines contents. Therefore, the system is divided into an air/combustion and a fuel/gasification reactor. Two gas streams are obtained separately. The two reactors are interconnected via loop seals to assure the global circulation of bed material and to avoid gas leakages from one reactor to the other. The global circulation rate is driven by the gas velocity in the air/combustion reactor. Furthermore, the fuel/gasification reactor itself is a circulating fluidized bed with the special characteristic of almost countercurrent flow conditions for the gas phase and bed material particles. By simple geometrical modifications, it is possible to achieve well-mixed flow conditions in the fuel/gasification reactor along the full height. The gas velocity and the geometrical properties in the fuel/gasification reactor are chosen in such a way that the entrainment of coarse particles is low at the top. Due to the dispersed downward movement of the bed material particles and the feedstock input at defined locations of the fuel/gasification reactor, no volatiles are produced in the upper regions and the problems of insufficient gas phase conversion and high tar contents are avoided.

Dissipation-scale fluctuations in the inner region of turbulent channel flow

The statistics of intense energy dissipation events in wall-bounded shear flows are studied using highly resolved direct numerical simulations of turbulent channel flow at three different friction Reynolds numbers. Distributions of the energy dissipation rate and local dissipation scales are computed at various distances from the channel walls, with an emphasis on the behavior of the statistics in the near-wall region. The dependence of characteristic mean and local dissipation scales on wall distance is also examined over the full channel height. Systematic variations in these statistics are found close to the walls due to the anisotropy generated by mean shear and coherent vortical structures. Results near the channel centerline are consistent with those found in homogeneous isotropic turbulence.

Comparing Steel Plate Shear Wall Behavior with Simple and Corrugated Plates

Experimental and numerical studies conducted in the past three decades have demonstrated that a steel plate shear wall is an effective and economical lateral load resisting system against both wind and earthquake forces. The system consists of infill steel plates connected to boundary beams and columns over the full height of the framed bay. The infill plates can be stiffened or unstiffened and the beam-to-column connections can be rigid or shear connections. A properly designed steel plate shear wall has superior ductility, high initial stiffness, stable hysteresis loops, and good energy absorption capacity. These characteristics make the system outstanding in high-risk seismic regions. Use of steel plate shear wall systems has been shown to be more cost effective than the other lateral load resisting systems. Steel plate shear walls are much lighter than the commonly used reinforced concrete shear walls, which reduce both the gravity loads and seismic forces. This aspect significantly reduces the foundation costs and makes the system outstanding for application in rehabilitation projects. Whereas construction cost of stiffened steel plate shear wall is more than unstiffened steel plate shear wall therefore in this investigation the unstiffened steel plate shear wall has been studied as two types of simple and corrugated plate and the behavior has been compared in one story frame. This study was conducted with finite element approach theoretically. The results of this study demonstrated that behavior of corrugated plate is superior to simple plate because it has high loading capacity, ductility and energy absorption.

Optical transmittance of photonic structures with logarithmically similar dielectricconstituents**This paper is dedicated to the memory of Dr E H Brandt, great scientist and dearfriend.

The optical transmittance of one-dimensional, logarithmically similar, layered stacks ofpairs of lossless dielectric plates for linearly polarized, normally incident electromagneticradiation is studied both analytically and numerically. Resorting to an analysis of therespective photonic modes, the dependence on frequency of the optical property addressedis established for a singly logarithmic stack as well as for two of its symmetric derivatives,an outbound doubly logarithmic stack and an inbound doubly logarithmic stack. Givenspecified constraints on the structural and dielectric parameters that delineate these stacks,the following key results come to the fore: the transmittance of the singly logarithmicstack shows single oscillatory maxima of almost full height at low frequencies andtotal quench at larger frequencies; the transmittance of the outbound doublylogarithmic stack shows twinned oscillatory maxima of full height at low frequencies,supplemented with a sharp, full resonance at a higher frequency against a background ofsuppressed transparency; the transmittance of the inbound doubly logarithmic stackshows twinned oscillatory maxima of full height at low frequencies, supplementedwith a series of pairs of sharp spikes of full transparency for higher frequenciesagainst a background of suppressed transparency. Thus, one-dimensional photonicstructures generated by logarithmically similar dielectric constituents are capable ofunfolding desirable and useful optical properties: transparency at low frequencies,but opacity, or selectivity, at higher frequencies, in one single photonic device.

Characterization of the flow past a truncated square cylinder in a duct under a spanwise magnetic field

AbstractWe study the flow of an electrically conducting fluid past a truncated square cylinder in a rectangular duct under the influence of an externally applied homogeneous magnetic field oriented along the cylinder axis. Our aim is to bridge the gap between the non-magnetic regime, where we previously found a complex set of three-dimensional recirculations behind the cylinder (Dousset &amp; Pothérat,J. Fluid Mech., vol. 653, 2010, pp. 519–536) and the asymptotic regime of dominating Lorentz force analysed by Hunt &amp; Ludford (J. Fluid. Mech., vol. 33, 1968, pp. 693–714). The latter regime is characterized by a remarkable structure known asHunt’s wakein the magnetohydrodynamics community, where the flow is deflected on either side of a stagnant zone, right above the truncated cylinder as if the latter would span the full height of the duct. In steady flows dominated by the Lorentz force, with negligible inertia, we provide the first numerical flow visualization of Hunt’s wake. In regimes of finite inertia, a thorough topological analysis of the steady flow regimes reveals how the Lorentz force gradually reorganizes the flow structures in the hydrodynamic wake of the cylinder as the Hartmann number$\mathit{Ha}$(which gives a non-dimensional measure of the magnetic field) is increased. The nature of the vortex shedding follows from this rearrangement of the steady structures by the magnetic field. As$\mathit{Ha}$is increased, we observe that the vortex street changes from a strongly symmetric one to the alternate procession of counter-rotating vortices typical of the non-truncated cylinder wakes.

Simplified dynamic analysis of eccentric buildings with a setback. 2: the effect of stiffness irregularity

SUMMARYThe effect of stiffness irregularity is investigated in eccentric buildings with a setback. Stiffness irregularity is assumed to be created when some of the lateral load resisting bents are curtailed at the top of the base structure. The methodology suggested in the companion paper for assessing vibration frequencies, base shears and torques is extended to include the effect of curtailed bents. Their contribution is evaluated by an indirect method after the modal stiffness of the symmetrical counterpart structure is determined and the modal contribution of the full height bents is assessed by Southwell's approach. A number of numerical examples, representing common types of building structures, are presented to illustrate the procedure and provide an insight into the response of such setback buildings. The results are compared with more accurate results obtained by three‐dimensional dynamic analyses. Copyright © 2009 John Wiley &amp; Sons, Ltd.