Structural Stability

This paper presents the theoretical basis for both static and dynamic numerical approaches to the elastic stability of a folding multi-layered truss. Both analyses are based on bifurcation theory and include geometrical nonlinearity. The dynamic analysis includes an allowance for contact between nodes. Comparisons are made between published experimental folding patterns and the patterns obtained from both numerical methods in which bifurcations are demonstrated as elastic unstable snap-through behaviour. Several folding patterns are identified during the elastic instability where the folding behaviour of the truss is shown to be a function of the initial geometry and velocity of the dynamic loading. The authors suggest that the understanding of the behaviour will be very useful for the development of light weight structures subject to dynamic loading based on the bifurcation static analysis and dynamic analysis (using both the displacement control method and the load control method). (I. Ario), [email protected] (A. Watson).

UV-vis and Raman spectroscopy were used to study iodine molecules trapped in sII clathrate hydrate structures stabilized by THF, CH 2 Cl 2 , or CHCl 3 . The spectra show that the environment for iodine inside the water cage is significantly less perturbed than either in aqueous solution or in amorphous water-ice. The resonance Raman progression of I 2 in THF clathrate hydrate can be observed up to V ) 6 when excited at 532 nm. The extracted vibrational frequency ω e ) 214 ( 1 cm -1 is the same as that of the free molecule to within experimental error. At the same time, the UV-vis absorption spectrum of I 2 in the sII hydrate exhibits a relatively large, 1440 cm -1 , blue-shift. This is mainly ascribed to the differential solvation of the I 2 electronic states. We conclude that iodine in sII hydrate resides in a 5 12 6 4 cavity, in which the ground-state I 2 potential is not significantly perturbed by the hydrate lattice. In contrast, in water and in ice, the valence absorption band of I 2 is dramatically broadened and blue-shifted by 3000 cm -1 , and the resonance Raman scattering is effectively quenched. These observations are shown to be consistent with a strong interaction between water molecule and iodine through the lone pair of electrons on water as in the case of bromine in the same media. The results presented here, and the stability of other halogen hydrates, were used to test the predictions of simple models and force-field calculations of the host cage-guest association energy.

Glucose oxidase from Aspergillus niger was purified to homogeneity by hydrophobic interaction and ion-exchange chromatography. Approx. 95% of the carbohydrate moiety was cleaved from the protein by incubation of glucose oxidase with endoglycosidase H and a-mannosidase. Cleavage of the carbohydrate moiety effected a 2 3-30% decrease in the molecular weight and a reduction in the number of isoforms of glucose oxidase. No si~atificant changes were observed in the circular dichroism spectra of the deglyeosylated enzyme. Other properties, such as thermal stability, pH and temperature optima of glucose oxidase activity and substrate specificity were not affected. However, removal of the carbohydrate moiety marginally affecled the kinetics of glucose oxidation and stability at low pH. From these results it appears that the carbohydrate chain of glucose oxidase does not contribute significantly to the structure, stability and activity of glucose oxidase.

Present study describes the development of a new formulation of levonorgestrel and ethinylestradiol based on double emulsion-solvent evaporation technique using poly(ε-caprolactone) (PCL) as biodegradable polymer. The effect of polymer concentration on microspheres and entrapment of drug into microspheres were studied. PCL was selected because of its hydrophobicity and advantages over other biodegradable polymers. Characterization of biodegradable polymer used for controlled drug delivery is essential to ensure reproducibility of in vitro and in vivo performances. The selected characterisation techniques established for PCL microspheres include its loading and entrapment efficiencies, DSC to analyse thermal behaviour, SEM to observe surface morphology, drug content of microspheres and in vitro release of drugs from microspheres. The SEM reports showed that microspheres were with smooth surface and DSC thermograms revealed no interaction between drug and polymer. The entrapment was found to be 58 and 47% for 1:10 and 1:5 batches and in vitro release studies showed that about 69.7% of LNG and 66.7% of EE from 1:10 batch and about 80% of LNG and 75.5% of EE from 1:5 batch for 150 days.

RNA folding is a kinetic process governed by the competition of a large number of structures stabilized by the transient formation of base pairs that may induce complex folding pathways and the formation of misfolded structures. Despite of its importance in modern biophysics, the current understanding of RNA folding kinetics is limited by the complex interplay between the weak base-pair interactions that stabilize the native structure and the disordering effect of thermal forces. The possibility of mechanically pulling individual molecules offers a new perspective to understand the folding of nucleic acids. Here we investigate the folding and misfolding mechanism in RNA secondary structures pulled by mechanical forces. We introduce a model based on the identification of the minimal set of structures that reproduce the patterns of force-extension curves obtained in single molecule experiments. The model requires only two fitting parameters: the attempt frequency at the level of individual base pairs and a parameter associated to a free energy correction that accounts for the configurational entropy of an exponentially large number of neglected secondary structures. We apply the model to interpret results recently obtained in pulling experiments in the three-helix junction S15 RNA molecule (RNAS15). We show that RNAS15 undergoes force-induced misfolding where force favors the formation of a stable non-native hairpin. The model reproduces the pattern of unfolding and refolding force-extension curves, the distribution of breakage forces and the misfolding probability obtained in the experiments.

The complement inhibitors C4b-binding protein (C4BP) and factor H (FH) both consist of complement control protein (CCP) domains. Here we examined the secondary structure of both proteins by circular dichroism and Fourier-transform infrared technique at temperatures ranging from 30°C-90°C. We found that predominantly ␤-sheet structure of both proteins was stable up to 70°C, and that a reversible conformational change toward ␣-helix was apparent at temperatures ranging from 70°C to 90°C. The ability of both proteins to inhibit complement was not impaired after incubation at 95°C, exposure to extreme pH conditions, and storage at room temperature for several months. Similar remarkable stability was previously observed for vaccinia virus control protein (VCP), which is also composed of CCP domains; it therefore seems to be a general property of CCP-containing proteins. A typical CCP domain has a hydrophobic core, which is wrapped in ␤-sheets and stabilized by two disulphide bridges. How the CCP domains tolerate harsh conditions is unclear, but it could be due to a combination of high content of prolines, hydrophobic residues, and the presence of two disulphide bridges within each domain. These findings are of interest because CCP-containing complement inhibitors have been proposed as clinical agents to be used to control unwanted complement activation that contributes to many diseases.

Spinel Co 3 O 4 and Li-doped Co 3 O 4 thin film electrocatalysts deposited on Pt and ITO/glass substrates were prepared by the sol-gel route from Co(II) sulfate precursor using dip-coating technique. Stoichiometry of undoped and Li + doped films (up to 10 mol% of Li + ) prepared at 300 and 500°C, respectively, showed deficiency with Co(III) ions in the film structure. All films exhibited substantial electrical conductivity (|) which was slightly dependent on the type of the substrate. The roughness factor, RF, of electrodes was determined by cyclic voltammetry. Spinel oxide films prepared at lower temperatures (300°C) showed high surface area (RF 700). The electrocatalytic properties were studied by different electrochemical methods in alkaline solutions. The results of electrochemical measurements in KOH indicated the formation of surface quasi-reversible redox couple, Co(IV)/Co(III), which is limited by a diffusion-controlled process. The oxygen evolution potentials pointed out remarkable performance of Co 3 − x O 4 (300°C) and Li + doped Co 3 − x O 4 (500°C) films. The reaction order with respect to [OH − ] was found to be nearly 1.2. Durability testing of films in 5 M KOH at 70°C showed high long-term performance and structure stability of Li + doped Co 3 − x O 4 (500°C) films.

The characterization and accurate determination of the chloride content in cement=concrete is very important for the assessment of the durability and safety of a concrete structure. The available analytical techniques are relatively expensive and time consuming. In this study, a laserinduced breakdown spectroscopy (LIBS) system was used for determination of elemental composition in three different types of cement samples. The plasma was generated by focusing a pulsed Nd: YAG laser at 1064 nm on the cement samples. The concentrations of different elements of significance for structural stability in cement samples were determined. The evaluation of the potential and the capabilities of LIBS as a rapid tool for characterization of cement samples is discussed. The optimum LIBS setup and experimental conditions to detect and measure chloride in building materials are reported. The LIBS results were compared with the results obtained using a standard analytical technique such as inductively coupled plasma emission spectroscopy (ICP-ES). The limits of detection were determined, and calibration curves were measured. The results of this investigation indicate the reliability of LIBS to characterize different cement samples and to assess the chloride content in these cements.

Since protein complex crystallization is expensive and time-consuming, computational docking tools provide a valuable method to investigate protein interactions. While the sampling of possible docked conformers of two proteins can be performed efficiently by Fast Fourier Transform (FFT) methods, the selection of near-native decoys from the pool of thousands of possible decoys is still far from being solved. Here, a new approach for docking decoy selection by Monte Carlo stability analysis is presented. In the course of replica exchange Monte Carlo simulations (REMC), replica from near-native decoys show a significantly lower structural diversity than replica from non-native decoys. The effect is successfully applied to rank docking decoys in a benchmark set of 59 protein complexes.

Although there has been a substantial increase over the past decade in studies that have examined the psychosocial correlates of spirituality/religiosity in adolescence, very little is known about spirituality/ religiosity as a domain of development in its own right. To address this limitation, the authors identified configurations of multiple dimensions of spirituality/religiosity across 2 time points with an empirical classification procedure (cluster analysis) and assessed development in these configurations at the sample and individual level. Participants included 756 predominately Canadian-born adolescents (53% female, 47% male) from southern Ontario, Canada, who completed a survey in Grade 11 (M age ϭ 16.41 years) and Grade 12 (M age ϭ 17.36 years). Measures included religious activity involvement, enjoyment of religious activities, the Spiritual Transcendence Index, wondering about spiritual issues, frequency of prayer, and frequency of meditation. Sample-level development (structural stability and change) was assessed by examining whether the structural configurations of the clusters were consistent over time. Individual-level development was assessed by examining intraindividual stability and change in cluster membership over time. Results revealed that a five cluster-solution was optimal at both grades. Clusters were identified as aspiritual/irreligious, disconnected wonderers, high institutional and personal, primarily personal, and meditators. With the exception of the high institutional and personal cluster, the cluster structures were stable over time. There also was significant intraindividual stability in all clusters over time; however, a significant proportion of individuals classified as high institutional and personal in Grade 11 moved into the primarily personal cluster in Grade 12.

Clause 6.3.4 of EN 1993-1-1 describes a “General Method” for lateral and lateral torsional
buckling of structural components, ideally suited to software applications. Although the
UK National Annex places some limitations on the use of this method, it is possible that
the approach will become more widely used. In the fist of two articles, Dr.József Szalai, of
ConSteel Solutions Ltd describes the background to the method.

First-principle calculations are carried out to investigate the structural, elastic and electronic properties of Fe 2 C. We use the plane-wavebased-pseudo-potential method, in which both the local-density approximation (LDA) and the generalized gradient approximation (GGA) implanted in the CASTP code are employed. The internal positions of atoms in the unit cell are optimized and the ground state properties such as lattice parameter, elastic constants, bulk modulus and the final enthalpy of g-Fe 2 C and e-Fe 2 C are calculated. The calculated values compare favorably with the available experimental data. From the calculated results, we confirm that the mechanical and energetic stability of g-Fe 2 C are prior to e-Fe 2 C at ambient conditions. The density of state (DOS) reveals that both g-Fe 2 C and e-Fe 2 C are strong metallic carbides. The electronic structure explains that the bonds of Fe 2 C are of the unusual mixtures of metallic, covalent, and ionic. It is found that the e-Fe 2 C has no magnetic character from the spin-polarized site-projected densities of states. The g-Fe 2 C has magnetic character with atom-averaged magnetic moment of 1.09 l B , which is little smaller than that within the Slater-Pauling-Friedel (SPF) model.

Soil fertility, one of the important determinants of agricultural productivity, is generally thought to be supplemented through the application of nutrients mainly through inorganic fertilizers. The physical fertility of the soil, which creates suitable environment for the availability and uptake of these nutrients, is generally ignored. The present study aims to characterize the soil physical environment in relation to the long term application of farm yard manure (FYM) and inorganic fertilizers in rice–wheat. The treatments during both rice and wheat crops were (i) farm yard manure @ 20 t ha−1 (FYM); (ii) nitrogen @ 120 kg ha−1 (N120); (iii) nitrogen and phosphorus @ 120 and 30 kg ha−1 (N120P30) and (iv) nitrogen, phosphorus and potassium @ 120, 30 and 30 kg ha−1 (N120P30K30) in addition to (iv) control treatment, i.e. without any fertilizer and/or FYM addition. The treatments were replicated four times in randomized block design in a sandy loam (typic Ustipsament, non-saline, slightly alkaline). Bulk density, structural stability of soil aggregates and water holding capacity of 0–60 cm soil layer were measured.The average mean weight diameter (MWD) was highest in FYM-plots both in rice (0.237 mm) and wheat (0.249 mm) closely followed by that in N120P30K30 plots. The effect of FYM in increasing the MWD decreased with soil depth. The addition of both FYM and N120P30K30 increased the organic carbon by 44 and 37%, respectively in rice. The total porosity of soil increased with the application of both FYM and N120P30K30 from that in control plots. In 0–15 cm soil layer, the total porosity increased by 25% with FYM from that in control plots. This difference decreased to 13% in 15–30 cm soil layer. The average water holding capacity (WHC) was 16 and 11% higher with FYM and N120P30K30 application from that in control plots. The MWD, total porosity and WHC improved with the application of balanced application of fertilizers. The grain yield and uptake of N, P and K by both rice and wheat were higher with the application of FYM and inorganic fertilizers than in control plots. The carbon sequestration rate after 32 years was maximum (0.31 t ha−1 year−1) in FYM-plots, followed by 0.26 t ha−1 year−1 in N120P30K30-plots, 0.19 t ha−1 year−1 in N120P30 and minimum (0.13 t ha−1 year−1) in N120-plots.

It is desirable to verify the structural performance based on a multi-hazard approach, taking into account the critical actions the structure in question could be subjected to during its lifetime. This study presents a proposal for a probabilistic model for multi-hazard risk associated with the limit state of collapse for a reinforced concrete (RC) structure subjected to blast threats in the presence of seismic risk. The annual risk of structural collapse is calculated taking into account both the collapse caused by an earthquake event and the blast-induced progressive collapse. The blast fragility is calculated using a simulation procedure for generating possible blast configurations, and verifying the structural stability under gravity loading of the damaged structure, using a kinematic plastic limit analysis. As a case study, the blast and seismic fragilities of a generic four-storey RC building located in seismic zone are calculated and implemented in the framework of a multi-hazard procedure, leading to the evaluation of the annual risk of collapse.

A modified synthesis process was developed based on co-precipitation method followed by spray drying process. In this process, a spherical shaped (Co 1/3 Ni 1/3 Mn 1/3 )(OH) 2 precursor was synthesized by co-precipitation and pre-heated at 500 °C to form a high structural stability ...

This work develops a singular perturbation theory for initial-value problems of nonlinear rst-order hyperbolic systems with sti source terms in several space variables. It is observed that under reasonable assumptions, many equations of classical physics of that type admit a structural stability condition. This condition is equivalent to the well-known subcharacteristic condition for one-dimensional 2 2-systems and the well-known time-like condition for scalar second-order hyperbolic equations with a small positive parameter multiplying the highest derivatives. Under this stability condition, we construct a formal asymptotic expansion for the solution to the nonlinear problems. Furthermore, assuming some regularity of the solutions to the limiting inner problems and the reduced problems, we prove the existence of classical solutions in the uniform time interval where the reduced problem has a smooth solution and justify the validity of the formal expansion.

Controlling seismic damage and improving performance are creative ideas of earthquake designing in which uses definite demonstrating of the structure together with techniques. One of the most important tools to dissipate energy is dampers that are able to reduce vibrations. Especially Fluid Viscous dampers (FVD) which are used to investigate the response of Reinforced Concrete building when they are subjected to lateral load like seismic. A structure might be viewed as serviceable in the event where it can be satisfied by transferring loads to foundation. Since earthquake loads are imposed on a structure, vibrations occur. To resist responses and absorb energy, Fluid Viscous Dampers is used. With Equivalent Static, Response Spectrum and Time history method, it is vital to identify characteristics by (ETABS) finite element program where Models having ordinary RC moment-resisting frame by square column cross-sections with and without FVD. In this evaluation, it is utilized in linear and non-linear analysis where ETABS, Version (18.0.2), has been used. The results are shown that dampers (FVD) dramatically reduce the lateral deflection and enhance the performance of the structure. They also cause a decrease in Time period of maximum Psuedo Spectral Acceleration (PSA) in Response spectrum curves, increasing the story stiffness and decreasing the story Shear. Therefore, adding FVD to RC buildings is effective utilization due to its dissipation of energy.

We investigate the binding surface along the Bain path and phonon dispersion relations for the cubic phase of the ferromagnetic binary alloys Fe3X (X = Ni, Pd, Pt) for L12 and DO22 ordered phases from first principles by means of density functional theory. The phonon dispersion relations exhibit a softening of the transverse acoustic mode at the M-point in the L12-phase in accordance with experiments for ordered Fe3Pt. This instability can be associated with a rotational movement of the Fe-atoms around the Ni-group element in the neighboring layers and is accompanied by an extensive reconstruction of the Fermi surface. In addition, we find an incomplete softening in [111] direction which is strongest for Fe3 Ni. We conclude that besides the valence electron density also the specific Fe-content and the masses of the alloying partners should be considered as parameters for the design of Fe-based functional magnetic materials.

The conformational stability of Shiga toxin B-subunit (STxB), a pentameric protein from Shigella dysenteriae has been characterized by high sensitivity differential scanning calorimetry and circular dichroism spectroscopy under different solvent conditions. It is shown that the thermal folding/unfolding of STxB is a reversible process involving a highly cooperative transition between folded pentamer and unfolded monomers. The conformational stability of STxB is pH dependent and because of its pentameric nature is also concentration dependent. STxB is maximally stable in the pH range from 5 to 9 (∆G upon unfolding is close to 13 kcal per mol of monomer at 25°C), and its stability decreases both at lower and at higher pH values. The pH dependence of the Gibbs energy of stabilization between pH 2.5 and 5 is consistent with the change in the ionizable state of an average of four groups per monomer upon unfolding. Structural thermodynamic calculations show that the stabilization of the STxB pentamer is primarily due to the interactions established between monomers rather than intramonomer interactions. The folding of an isolated monomer into the conformation existing in the pentamer is unfavorable and expected to be characterized by a free-energy change upon folding in the order of 2.5 kcal mol -1 at 25°C. On the average, intersubunit interaction induced upon oligomerization of folded monomers should contribute close to -13.4 kcal per mol of monomer to bring the overall Gibbs energy to the experimentally determined value at this temperature. † reticulum; DSC, differential scanning calorimetry; UV CD, ultraviolet circular dichroism; ∆G, Gibbs free energy of protein unfolding; ∆Cp, heat capacity change; Gdn-HCl, guanidine hydrochloride; ASA, accessible surface area.

a b s t r a c t Seeds die inevitably but unexpectedly during storage and current understanding of seed quality and storage conditions do not allow reliable means to predict or prevent this critical problem. Chemical degradation of seed components likely occurs through oxidative damage, but the rate of these reactions is dominated by properties of seed that are affected by temperature and moisture. These visco-elastic properties contribute to the structure of seeds as amorphous solids. This paper presents the perspective of seed maturation and post-harvest treatment as an exercise in engineering design for a structure that must persist through time and fluctuating conditions. Structural analyses are engineering tools used to select proper composition of materials and predict their behavior under a range of circumstances and are applicable to measurement within seeds. Thermal mechanical analysis (TMA) and dynamic mechanical analysis (DMA) measure structural deformation and stress-strain relationships, providing sensitive and universal parameters that detect differences in structural stability in materials with subtle compositional differences or processing methods. When applied to seeds, TMA and DMA techniques provide information consistent with existing information on glass and first order transitions. The depth of additional information obtainable about the behavior of the glass and interactions with lipid structure suggests that these techniques will be able to quantify differences among seed structures that contribute to their tendency to age.

The paper deals with the comparative study of nanocrystalline Lanthanum hexaboride (LaB 6 ) thin films grown on various substrates by Pulsed laser deposition and Arc plasma method. Field emission studies were carried out on LaB 6 films deposited on various substrates show metallic behavior of the emitters. The high value of field enhancement factors, indicating that the electron emission from LaB 6 nanoscale protrusions deposited on emitter surface. The post field emission surface morphology of the emitters showed no significant erosion of the films during continuous operation. The observed behavior indicates that it is linked with the growth of LaB 6 films on substrate crystal structure. The LaB 6 nanocrystallites/nanowires films were synthesized using arc plasma method shows good emission current stability. The LaB 6 micro/nanocrystallites were also obtained by picosecond laser irradiation which gives high enhancement β factor, and good emission current stability along with high current density. The results reveal that nanocrystalline LaB 6 films, exhibit high resistance to ion bombardment and excellent structural stability and are more promising emitters for practical applications in field emission based new generation devices.

In this paper we examine the ability to perform causal reasoning with recursive equilibrium models. We identify a critical postulate, which we term the Manipulation Postulate, that is required in order to perform causal inference, and we prove that there exists a general class F of recursive equilibrium models that violate the Manipulation Postulate. We relate this class to the existing phenomenon of reversibility and show that all models in F display reversible behavior, thereby providing an explanation for reversibility and suggesting that it is a special case of a more general and perhaps widespread problem. We also show that all models in F possess a set of variables V’ whose manipulation will cause an instability such that no equilibrium model will exist for the system. We define the Structural Stability Principle which provides a graphical criterion for stability in causal models. Our theorems suggest that drastically incorrect inferences may be obtained when applying the Manipulation Postulate to equilibrium models, a result which has implications for current work on causal modeling, especially causal discovery from data.

The aim of the paper is to describe hydraulic stability of rock-armoured low-crested structures on the basis of new experimental tests and prototype observations. Rock armour stability results from earlier model tests under non-depth-limited long-crested head-on waves are reviewed.

The structural stability of transcriptionally inert paternal chromatin is of vital importance for the fertilization process and early embryonic development. Accordingly, a series of eight experiments were conducted during a 7-month period to investigate: (1) effects of bull breed, individuality, successive ejaculations, semen quality characteristics (SQC), semen dilution rates and hypothermic storage of semen in a Tris-egg yolk extender on incidence of sperm nuclear chromatin instability (NCI), and (2) effects of the interaction between variation of NCI within a frozen ejaculate and variation of oocytes quality due to maturation time and/or season on the efficiency of in vitro embryo production (IVEP). Semen samples were collected once a week from six bulls using an AV and only ejaculates (n = 220) of >0.30 × 10 9 sperm/ml and ≥60% motility were used. NCI was measured by: (1) detection of lysine-rich histones in sperm chromatin using aniline blue staining, (2) sperm susceptibility to acid-induced nuclear DNA denaturation in situ using acridine orange test, and (3) sperm susceptibility to nuclear chromatin decondensation (NCD). Bovine oocytes (n = 695) were matured in vitro for 18 or 24 h, fertilized after sperm selection through a swim-up procedure and cultured for 72 h. The results showed that the 2nd ejaculates were superior to the 1st ones with respect to chromatin stability. Dilution of semen to 49.67 ± 8.56 × 10 6 sperm/ml (1:19) decreased resistance of sperm to NCD. Cooling of semen had no significant effect on chromatin stability. Cryopreservation of semen augmented sperm vulnerability to DNA denaturation. Improvement of SQC (semen volume, sperm motility, velocity, viability and morphological normalcy) was generally concomitant with increase of sperm resistance to NCI. While Blonde d'Aquitaine bulls had a resistance to NCD higher than Limousine bulls in fresh semen, the former showed a greater susceptibility to DNA denaturation than the latter in cooled semen. Individuality * Corresponding author. Present address: c/o Christine significantly influenced NCI. The variability of NCI within a frozen ejaculate affected efficiency of IVEP. Significant negative correlations were observed between incidence of NCI and both fertilization rate and developmental capacity of embryos after maturation of oocytes for 18 h. The significant variation in IVEP traits due to season was independent of the effect of sperm chromatin instability.

The three-dimensional structure of a galactomannan has been determined by careful analysis of the X-ray data obtained from polycrystalline and well oriented fibers of guaran. The polymer forms a flat 2-fold helix of pitch 10.38 A. The galactosyl side-chain hydrogen bonds to the mannan backbone intramolecularly and provides structural stability. Four helices Ž are packed in an orthorhombic unit cell of dimensions a s 9.26, b s 30.84 and c fiber . axis s 10.38 A according to space group symmetry I 222. Each chemical repeat consisting of 1.0 mannosyl and 0.6 galactosyl units is associated with two structured water molecules which are responsible for the formation and stability of sheets of guaran helices in the crystalline lattice. The crystallographic R-value is 0.185 for the best model. The guaran molecular structure and packing arrangement presented here are readily adoptable to the entire galactomannan family. q

Ground deformation monitoring in tunnelling is a common means for selecting and controlling the excavation and support methods among those predicted in design, ensuring safety during tunnel excavation (including personnel safety inside the tunnel and safety of structures located at ground surface) and construction quality. This paper describes the types of ground deformation measurement often used in tunnelling, the difficulties in obtaining these measurements, the methods most commonly used for their evaluation, and the use of deformation measurements (a) in the selection of tunnel excavation and support systems and (b) in establishing early warning systems against ground collapse or damage to structures at ground surface.

Eurocode 4 is the European design code for composite construction ; in its so-called ENV version (ENV 1994) (Eurocode 4 1992), the scope is limited to "non-sway buildings" with efficient bracing systems. Therefore, it gives mainly rules to analyze and to check structural elements like beams, columns, slabs and joints. However, in the last years, the construction of taller buildings and larger industrial halls without wind bracing systems is susceptible to make global instability a relevant failure mode, which is not covered by Eurocode 4 ENV 1994. For three years, in the framework of a European research project funded by the European Community for Steel and Coal (ECSC), in which the university of Liège was deeply involved, intensive experimental, numerical and theoretical investigations have been carried out. The latter aimed at improving the knowledge in the field of sway composite frames and at developing appropriate design rules. The rotational behavior of the beam-to-column composite joints is one of the key aspects of the problem to which a special attention has been paid.

Il volume introduce all'ampia problematica dell'analisi non lineare delle strutture, essenziale per giungere ad una stima delle loro capacità portante e definirne la sicurezza rispetto al collasso.

L'attenzione è posta in particolare sull'analisi del comportamento elasto-plastico  e sull'analisi dei fenomeni di instabilità delle strutture, con riferimento quindi a strutture tozze dove sono prevalenti le non linearità fisiche del materiale di cui sono composte, e a strutture snelle dove le non linearità prevalenti sono di tipo geometrico legate ai concetti di instabilità delle relative configurazioni di equilibrio.

L'approccio non lineare all'analisi delle strutture, per l'impegno di calcolo notevolmente più pesante di quello richiesto da analisi a base convenzionale,  è conseguibile solo nel quadro di una strategia numerica di tipo automatico di analisi. A tal fine le metodologie di analisi non lineare sviluppate nel testo sono finalizzate ad una implementazione automatica nel quadro di una strategia di discretizzazione agli elementi finiti.

Mentre fino a pochi anni addietro tale approccio risultava di interesse specialistico o accademico, la potenza di calcolo e la diffusione dei nuovi microcalcolatori a basso costo rende adesso possibile, e lo renderà sempre più tra breve, un uso generalizzato di procedimenti di verifica strutturali basati su analisi di tipo non lineare.

The work in this report represents how wind turbine towers are designed to give maximum stability in extreme conditions. Different stability criterion are explained and analyzed both analytically and numerically with the help of different standards (euro codes, AISC). For numerical analysis all task are performed on finite element package Abaqus. Two different tubular tower models are first analyzed and checked whether they satisfied stability criterions (deflection, local buckling). It was found that the both the towers are safe against the local buckling and stable under the extreme wind loading. The methodologies adopted in designing wind turbine tower to achieve an optimized result like, minimization of mass, maximization of natural frequency or maximization of stiffness at the end of the report is done. During optimization is observed that the 250kw tower model gives economical result if its design for the variable thickness i.e. less material required for manufacture which reduces its cost.

In order to investigate the validity of a coupled mill vibration model presented in the dynamic rolling formulation, this paper presents the results of dynamic characteristics examining rolling force variations in response to rolling parameters. Under the given steady state rolling condition, the unstable vibrational modes with corresponding frequencies are identified and stability analysis is also performed to demonstrate that the proposed model is highly dependent on the rolling speed and friction coefficient with an assumed negative gradient of friction coefficient. To further find the transient characteristics and the direct influences of the friction coefficient and rolling speed on the mill chatter, the derived equations of motion of the system are solved using Runge-Kutta numerical integration method. Simulations are carried out to reveal the chatter sources, which gives rise to unstable rolling vibrations. INTRODUCTION Mathematical models representing the cold rolling mechanism have attracted extensive attention, resulting in analytical, numerical or graphical solutions achieved under a variety of assumptions and simplifications. One of the important parts in modeling chatter mechanism is to establish a well-defined dynamic model of the rolling process that entails complicated relationship between rolling variables. A model that presents the rolling force as a function of rolling variables must explain dynamic interactions between the rolling process

This paper presents the main features and organization of CADAM, a computer program that has been developed for the static and seismic stability evaluations of concrete gravity dams. CADAM is based on the gravity method using rigid body equilibrium and beam theory to perform stress analyses, compute crack lengths, and safety factors. Seismic analyses could be done using either the pseudo-static or a simplified response spectrum method. CADAM is primarily designed to provide support for learning the principles of structural stability evaluation of gravity dams. It could also be used for research and development on stability of gravity dams. In adopting several worldwide published dam safety guidelines, a large number of modeling options have been implemented regarding (a) crack initiation and propagation, (b) effects of drainage and cracking under static, seismic, and post-seismic uplift pressure conditions, and (c) safety evaluation formats (deterministic allowable stresses and limit states, probabilistic analyses using Monte Carlo simulations). Structural stability evaluation of a 30m dam is presented to illustrate the use of CADAM that is available free from the web site:

This paper employs the recently developed structural stability test with multiple regime shifts and grid bootstrapping methods to model US inflation dynamics over the past half century. Our empirical results suggest that the persistence of inflation has witnessed significant declines over the most recent period of low inflation and this helps to embed a low inflation environment. The finding is

Today the use of glass into the edil sector is not only related to the facade application. In fact, glass as a structural material is always more largely used e.g. as beam and plate elements
that are able to carry loads. Their structural interaction is often due to mechanical connections.
This work has been written to analyse and to implement the knowledge about the flexo-torsional stability of these structural elements. Based on earlier contributions of literature and
extended parametric Finite-Element (FE) numerical investigation, a little gap is presented between the analytic and numerical analysis of the beneficial contribution to the structural
glass beam stability by the lateral restraints. This gap is due to the local effects around lateral mechanical restraints. This difference comes to light when we design the connectors. At first, they are designed like a punctual restraint and at the latter like a hole. In conclusion, a generalized buckling design curve, able to account for the structural contribution and provided by structural mechanical joints is proposed for a rational and conservative LTB verification. This verification is made by a comparison between analytic and numerical simulations outputs.

The stability of steel beams with discrete lateral restraints is analysed using the Rayleigh–Ritz method, with the degrees-of-freedom being represented by Fourier series. Linear eigenvalue analysis of the system shows that the system buckles into one of two classes of mode, either node-displacing or between bracing nodes. Buckling mode progression behaviour is examined and limiting characteristics of the system are found. Comparison is made with a single harmonic representation of the DOFs, which is found to lead to erroneous predictions. Validation of the analysis is performed using the finite element method and numerical continuation. Finally, it is shown that design formulae based on analogous column behaviour can return both conservative and unsafe results, depending on brace location.

This paper summarizes for practitioners the key recommendations of a recent ASCE report for utilizing the notional load approach to design steel columns in unbraced frames.  This method, which has been employed successfully outside the United States, involves the addition of a lateral load to each story and column line which is proportional to the total gravity load applied to it at that level.  The main advantage of the notional load approach is that it eliminates the need to calculate effective length factors.  Sway stability effects are accounted for by increasing the applied moments in the beam-column interaction equations, rather than by reducing the axial capacity.

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