Part Of Shell Research Articles

Dynamics of water in conical solvation shells around a benzene solute under different thermodynamic conditions.

Water molecules in different parts of the anisotropic hydration shell of an aromatic molecule experience different interactions. In the present study, we investigate the anisotropic dynamics of water molecules in different non-overlapping conical shells around a benzene solute at sub- and supercritical conditions by means of molecular dynamics simulations using both non-polarizable and polarizable models. In addition to the dynamical properties, the effects of polarizability on the hydration structure of benzene at varying thermodynamic conditions are also investigated in the current study. The presence of πH-bonding in the solvation shell is found to be an important factor that influences the anisotropic dynamics of the benzene hydration shell. The water molecules located axial to the benzene plane are found to be maximally influenced by the πH-bonding. The extent of πH-bonding is found to be somewhat reduced on inclusion of polarizability. The πH-bonded water molecules are found to reorient through large-amplitude angular jumps where the jump-angle amplitude increases at higher temperatures and lower densities. For both non-polarizable and polarizable models, it is found that the water molecules in the axial conical shells possess faster orientational and hydrogen bond dynamics compared to those in the equatorial plane. Water molecules in the axial conical shells are also found to diffuse at a faster rate than bulk molecules due to the relatively weaker benzene-water πH-bonding interactions in the axial region of the hydration shell. The residence dynamics of water molecules in different conical solvation shells around the solute is also investigated in the current study.

Interstellar gas and X-rays toward the Young supernova remnant RCW 86; pursuit of the origin of the thermal and non-thermal X-ray

We have analyzed the atomic and molecular gas using the 21 cm Hi and 2.6/1.3 mm CO emissions toward the young supernova remnant (SNR) RCW 86 in order to identify the interstellar medium with which the shock waves of the SNR interact. We have found an Hi intensity depression in the velocity range between −46 and −28 kms−1 toward the SNR, suggesting a cavity in the interstellar medium. The Hi cavity coincides with the thermal and non-thermal emitting X-ray shell. The thermal X-rays are coincident with the edge of the Hi distribution, which indicates a strong density gradient, while the non-thermal X-rays are found toward the less dense, inner part of the Hi cavity. The most significant non-thermal X-rays are seen toward the southwestern part of the shell where the Hi gas traces the dense and cold component. We also identified CO clouds which are likely interacting with the SNR shock waves in the same velocity range as the Hi, although the CO clouds are distributed only in a limited part of the SNR shell. The most massive cloud is located in the southeastern part of the shell, showing detailed correspondence with the thermal X-rays. These CO clouds show an enhanced CO J=2–1/1–0 intensity ratio, suggesting heating/compression by the shock front. We interpret that the shock-cloud interaction enhances non-thermal X-rays in the southwest and the thermal X-rays are emitted by the shock-heated gas of density 10–100 cm−3. Moreover, we can clearly see an Hi envelope around the CO cloud, suggesting that the progenitor had a weaker wind than the massive progenitor of the core-collapse SNR RX J1713.7–3949. It seems likely that the progenitor of RCW 86 was a system consisting of a white dwarf and a low-mass star with low-velocity accretion winds.

Physical conditions for Jupiter-like dynamo models

The Juno mission will measure Jupiter’s magnetic field with unprecedented precision and provide a wealth of additional data that will allow us to constrain the planet’s interior structure and dynamics. Here we analyse 66 different numerical simulations in order to explore the sensitivity of the dynamo-generated magnetic field to the planets interior properties. Jupiter field models based on pre-Juno data and up-to-date interior models based on ab initio simulations serve as benchmarks. Our results suggest that Jupiter-like magnetic fields can be found for a number of different models. These complement the steep density gradients in the outer part of the simulated shell with an electrical conductivity profile that mimics the low conductivity in the molecular hydrogen layer and thus renders the dynamo action in this region largely unimportant. We find that whether we assume an ideal gas or use the more realistic interior model based on ab initio simulations makes no difference. However, two other factors are important. A low Rayleigh number leads to a too strong axial dipole contribution while the axial dipole dominance is lost altogether when the convective driving is too strong. The required intermediate range that yields Jupiter-like magnetic fields depends on the other system properties. The second important factor is the convective magnetic Reynolds number radial profile Rmc(r), basically a product of the non-axisymmetric flow velocity and electrical conductivity. We find that the depth where Rmc exceeds about 50 is a good proxy for the top of the dynamo region. When the dynamo region sits too deep, the axial dipole is once more too dominant due to geometric reasons. Extrapolating our results to Jupiter and the result suggests that the Jovian dynamo extends to 95% of the planetary radius.The zonal flow system in our simulations is dominated by an equatorial jet which remains largely confined to the molecular layer. Where the jet reaches down to higher electrical conductivities, however, it gives rise to a secondary αΩ dynamo that modifies the dipole-dominated field produced deeper in the planet. This secondary dynamo can lead to strong magnetic field patches at lower latitudes that seem compatible with the pre-Juno field models.

Water structure around hydrophobic amino acid side chain analogs using different water models.

The water structure around hydrophobic groups governs various biochemical processes. There is an ongoing debate on whether water molecules near hydrophobic groups are more ordered with greater participation in water-water hydrogen bonding with respect to water in the pure bulk state. The water structure around six different hydrophobic amino acid side chain analog molecules has been studied in pure water using molecular dynamics simulations. The analysis of water tetrahedral order parameter and the number of hydrogen bonds formed by the individual water molecules in the first hydration shell of the hydrophobic analogs provide evidence that both ordering and hydrogen bonds involving water molecules are to some extent reduced in the hydrophobic hydration shell. It is revealed that the water tetrahedrality in the outer part of the first hydrophobic hydration shell is equivalent to bulk water for all the water models except for the TIP4P-2005 model which shows marginally higher tetrahedrality. However, irrespective of the model employed, water tetrahedrality has always been found to be reduced in the inner part of the first hydration shell, which eventually makes the overall water tetrahedrality in the first hydrophobic hydration shell marginally lower than that observed for pure bulk water. Importantly, it is noticed that the decrease in water structuring exhibits solute size dependencies. Around a small solute like methane, the water tetrahedral ordering or hydrogen bonding propensity is quite similar to that of the bulk state. The effect, reduction in water structuring, is however more pronounced for relatively larger solutes.

Smart shell membrane prepared by microfluidics with reactive nematic liquid crystal mixture

Smart, uniform-sized, solid-state nematic liquid crystal (NLC) (NLCsolid) shell membranes were successfully fabricated from a reactive mesogen mixture (RMM727) and 4-cyano-4′-pentylbiphenyl (5CB) using a microfluidic method that combines flow-focusing and co-flow glass capillary geometries after UV curing and 5CB extraction. The NLC shells having planar anchoring with poly(vinyl alcohol) (NLCp shells) showed unavoidable defects as per the Poincaré theorem, with a total of +2 defect strengths on the top of the shell (often the weakest point of the shell), and were usually ripped during UV curing. The NLC shells having homeotropic anchoring with sodium dodecyl sulfate/polysorbate 80 (1/1, w/w) (NLCh shells) had a defect-free structure and could be formed into NLCsolid shells without ripping when the density of the RMM727/5CB mixture matched that of the aqueous medium in the microfluidic channel (controlled using a glycerol/water mixture). The thin part of the NLCh shell was easily ripped during UV curing without density matching. The thus-produced NLCsolid shells exhibited good swelling/shrinkage properties depending on the solvent quality and temperature, which could be further utilized for encapsulating/releasing Rhodamine 6G in/from the core of the NLCsolid shell. The pores in the NLCsolid shell (the size of which was controlled by the 5CB content of the RMM727/5CB mixture) were completely closed in a poor solvent and open in a good solvent. The encapsulation/release properties were studied based on the fluorescence intensity of encapsulated Rhodamine 6G. This study provides a method for preparing uniform-sized and robust NLCsolid shell membranes that can be used for several applications, such as in smart actuators, sensors, and parts of microelectromechanical systems.

Collateralization of projections from the paraventricular nucleus of the thalamus to the nucleus accumbens, bed nucleus of the stria terminalis, and central nucleus of the amygdala.

The paraventricular nucleus of the thalamus (PVT) is a midline thalamic nucleus with dense projections to the nucleus accumbens (NAc), dorsolateral region of the bed nucleus of the stria terminalis (BSTDL) and the lateral/capsular region of the central nucleus of the amygdala (CeL/CeC). Recent experimental evidence indicates that the PVT is involved in both appetitive and aversive behaviors. However, it is unknown if subgroups of neurons in the PVT innervate different subcortical targets or if the same neurons issue collaterals to multiple areas. To address this issue, we injected two different fluorescent retrograde tracers, cholera toxin subunit B conjugated to Alexa Fluor-488 or Alexa Fluor-594, into different pairs of the subcortical targets including different parts of the NAc (shell, core, dorsomedial shell, and ventromedial shell), BSTDL, and amygdala (basolateral amygdala and CeL/CeC). The results indicate a moderate to high level of collateralization of projections from neurons in the PVT to NAc, BSTDL, and CeL/CeC suggesting a potential importance of the PVT in simultaneously coordinating the activity of key regions of the brain involved in mediating emotional and motivational behaviors. We also observed a difference in the subcortical targets innervated by the anterior PVT (aPVT) and posterior PVT (pPVT) showing that more neurons in the aPVT innervate the dorsomedial part of the NAc shell, while more neurons in the pPVT innervate the ventromedial NAc shell, BSTDL, and CeL/CeC. This observation is suggestive of a potential functional difference between the aPVT and pPVT.

Investigation of the Free Vibrations of Composite Anisogrid Lattice Conical Shells Formed by Geodesically Spiral and Circumferential Ribs

This paper focuses on the dynamic behavior of composite anisogrid lattice conical shells. Lattice composite conical shell consists of composite helical and circumferential ribs and thin outer skin. The free vibration analysis of anisogrid composite lattice conical shell is presented. A smeared method is employed to calculate the variable coefficients of stiffness of conical shell and more close to the realistic applications. The lattice part of conical shell is modeled as a beam, so in addition to the axial loads, ribs endure shear loads and bending moments. The first-order shear deformation shell theory is used to account for the effects of transverse shear deformations and rotary inertia. The current results are verified with 3D finite element model of conical shell by ANSYS Software and those reported in the literature. Some special cases as influences of geometric parameters of lattice part of shell, effects of boundary conditions and circumferential wave number on natural frequencies of the shell are discussed. It was concluded that employment of the smear method could be recommended for determining the coefficients of stiffness of the composite lattice conical shells with outer skin. Also increasing the vertex angle of cone increases the natural frequencies of conical shell.

Tuning spontaneous radiation of chiral molecules by asymmetric chiral nanoparticles.

We have obtained analytical expressions for the radiative decay rate of the spontaneous emission of a chiral molecule located near a dielectric spherical particle with a chiral nonconcentric spherical shell made of a bi-isotropic material. Our numerical and graphical analyses show that material composition, thickness and degree of non-concentricity of the shell can influence significantly the spontaneous radiation of the chiral molecule. In particular, the radiative decay rates can differ in orders of magnitude for a chiral molecule located near the thin and thick parts of a nonconcentric shell as well as near a concentric shell made of chiral metamaterial. We also find that the radiative decay rates of the "right" and "left" chiral molecule enantiomers located near a nanoparticle with a chiral metamaterial shell can differ pronouncedly from each other. Our findings therefore suggest a way to tune the spontaneous emission of chiral molecules by varying the material composition, thickness and degree of non-concentricity of the shell in the nearby composite nanoparticle and also to enhance the chirality selection of chiral molecules in racemic mixtures.

Water Dynamics in Cytoplasm-Like Crowded Environment Correlates with the Conformational Transition of the Macromolecular Crowder.

Polyethylene glycol (PEG) is a unique polymer material with enormous applicability in many industrial and scientific fields. Here, its use as macromolecular crowder to mimic the cellular environment in vitro is the focus of the present study. We show that femtosecond mid-IR pump-probe spectroscopy using three different IR probes, HDO, HN3, and azido-derivatized crowder, provides complete and stereoscopic information on water structure and dynamics in the cytoplasm-like macromolecular crowding environment. Our experimental results suggest two distinct subpopulations of water molecules: those that interact with other water molecules and those that are part of a hydration shell of crowder on its surface. Interestingly, water dynamics even in highly crowded environment remains bulk-like in spite of significant perturbation to the tetrahedral H-bonding network of water molecules. That is possible because of the formation of water aggregates (pools) even in water-deficient PEGDME-water solutions. In such a crowded environment, the conformationally accessible phase space of the macromolecular crowder is reduced, similar to biopolymers in highly crowded cytoplasm. Nonetheless, the hydration water on the surface of crowders slows down considerably with increased crowding. Most importantly, we do not observe any coalescing of surface hydration water (of the crowder) with bulk-like water to generate collective hydration dynamics at any crowder concentration, contrary to recent reports. We anticipate that the present triple-IR-probe approach is of exceptional use in studying how conformational states of crowders correlate with structural and dynamical changes of water, which is critical in understanding their key roles in biological and industrial applications.

Nature of the turtle shell: Morphogenetic causes of bone variability and its evolutionary implication

The turtle shell is characterized by a high degree of conservatism of the fundamental model and, at the same time, a high variability at the individual level. The components of the bony shell vary in origin. The costal and neural plates of the carapace are modified elements of the axial skeleton (ribs and neural arches) and the plastral plates are transformed dermal ossifications of the shoulder girdle and gastralia, peripheral, pygal, and suprapygal plates are similar to osteoderms of other reptiles. The variability of the structure of particular parts of the turtle shell is manifested differently. Most anomalies have been recorded in the caudal part of the carapace. The plastron is relatively stable in morphology. Variations in the bony shell structure are observed in (1) unusual shape and size of plates combined with normal number of plates, (2) presence of additional plates, and (3) absence of regular plates. Based on the morphogenetic characteris-tics, anomalies are subdivided into (1) variations caused by changes in the number of elements of the axial skeleton or their contacts with the dermis (neurals and costals); (2) variations due to changes in the number of horny scutes (peripherals); (3) variations connected with irregular osteogeny or disturbed growth of bones

Use of XPS thermal insulator boards in design of educational spaces

This research refers to case study, Haghpanah girls' primary school that is of the standard schools designed and implemented by Isfahan Province Schools Renovation Organization. It deals to the importance and creation of an operational method for applying modern materials such as XPS thermal insulator in architectural design and its effect on educational spaces in section of primary school and how to design. It also deals to its effect and advantages on interior spaces that will help educational optimization significantly. Perhaps some believe that the implementation of thermal insulation of the building increases construction costs. However, we note that the implementation of thermal insulation not only saves energy consumption but also has a significant role in consumption of wasted heating and cooling energy of educational spaces. For example, the position of mentioned school is on the ground floor (pilot) and with external walls around the building. As it is obvious, the building floor and three sides of its perimeter are a part of the external shell (in contact with the outside perimeter). Cooling and heating of such a building requires spending high costs to provide equipment with high capacities. Heating and cooling equipment capacity becomes smaller than half after proper implementation of thermal insulation. As air conditioning equipment becomes small, implementation of optimization not only becomes free but also reduces the overall cost of construction. Keywords: School, modern materials, Building and Housing Research Center, XPS boards

Transient inactivation of the nucleus accumbens (NAc) shell prominently ameliorates responses to acute stress in female rats

It is clear that the stress response differs between females and males. Moreover, the nucleus accumbens shell is considered a critical area in the brain's response to stress. In the present study we investigate the effect of the transient inactivation of the NAc shell on the metabolic and hormonal disturbance induced by acute stress in female rats. Female Wistar rats were canulated uni- or bilaterally in the NAc shell before stress induction. Electric foot shock was applied to the animals and lidocaine hydrochloride was administered intra-acumbally 5min before each stress session. Food and water intake, delay to eating time, plasma corticosterone, estradiol and progesterone were measured after stress administration. Our results indicate that food intake increased whereas water intake decreased in stress group, furthermore, delay in the onset of eating also was observed. In addition, plasma corticosterone and progesterone concentrations were increased whereas estradiol was decreased. Transient inactivation of right side of NAc shell inhibited the stress effect on food intake; however, the effect of stress was exacerbated when the left part of the NAc shell was inhibited. Transient inactivation of both NAc shell sides augmented the stress effect on water intake. The same results also obtained for the effect of stress on delay to eating time. Lidocaine administration inhibited the effects of stress on all of the hormones we tested. It can be concluded that the NAc shell plays an important role in the mediation of stress responses in female rats and this influence shows asymmetrical manner.

Hybrid MC/QC simulations of water-assisted proton transfer in nucleosides. Guanosine and its analog acyclovir

To provide an in-depth insight into the molecular basis of spontaneous tautomerism in DNA and RNA base pairs, a hybrid Monte Carlo (MC)–quantum chemical (QC) methodology is implemented to map two-dimensional potential energy surfaces along the reaction coordinates of solvent-assisted proton transfer processes in guanosine and its analog acyclovir in aqueous solution. The solvent effects were simulated by explicit inclusion of water molecules that model the relevant part of the first hydration shell around the solute. The position of these water molecules was estimated by carrying out a classical Metropolis Monte Carlo simulation of dilute water solutions of the guanosine (Gs) and acyclovir (ACV) and subsequently analyzing solute–solvent intermolecular interactions in the statistically-independent MC-generated configurations. The solvent-assisted proton transfer processes were further investigated using two different ab initio MP2 quantum chemical approaches. In the first one, potential energy surfaces of the ‘bare’ finite solute–solvent clusters containing Gs/ACV and four water molecules (MP2/6-31+G(d,p) level) were explored, while within the second approach, these clusters were embedded in ‘bulk’ solvent treated as polarizable continuum (C-PCM/MP2/6-31+G(d,p) level of theory). It was found that in the gas phase and in water solution, the most stable tautomer for guanosine and acyclovir is the 1H-2-amino-6-oxo form followed by the 2-amino-6-(sZ)-hydroxy form. The energy barriers of the water-assisted proton transfer reaction in guanosine and in acyclovir are found to be very similar – 11.74 kcal mol−1 for guanosine and 11.16 kcal mol−1 for acyclovir, and the respective rate constants (k = 1.5 × 101 s−1, guanosine and k = 4.09 × 101 s−1, acyclovir), are sufficiently large to generate the 2-amino-6-(sZ)-hydroxy tautomer. The analysis of the reaction profiles in both compounds shows that the proton transfer processes occur through the asynchronous concerted mechanism.

Modeling red coral (Corallium rubrum) and African snail (Helixia aspersa) shell pigments: Raman spectroscopy versus DFT studies

Pigments from red coral (Corallium rubrum) and African snail (Helixia aspersa) shell were studied non‐invasively using Raman spectroscopy with 1064‐nm laser beam. The two observed bands because of organic pigments confined in biomineralized CaCO3 matrix at about 1500 and 1100 cm−1 were assigned to ν(CC) and ν(C―C), respectively. Both signals originate from polyene(s) of largely unknown structure, containing several conjugated CC bonds. The small peak at 1016 cm−1 in the Raman spectrum of coral pigment was assigned to in‐plane ―CH3 rocking or structural deformation of polyene chain because of spatial confinement in the mineral matrix. The organic pigments in red coral and snail shell were present in inorganic matrix containing aragonite (shell) and calcite (coral). In addition, using Raman spectroscopy, it was observed that aragonite was replaced by calcite as result of healing damaged parts of snail shell. This is an important finding which indicates a great potential of nondestructive Raman spectroscopy instead of X‐ray technique, as a diagnostic tool in environmental studies. To support analysis of the observed Raman spectra detailed calculations using density functional theory (DFT with B3LYP and BLYP density functionals) on structure and vibrations of model all‐trans polyenes were undertaken. DFT calculated CC and C―C stretching frequencies for all‐trans polyenes containing from 2 to 14 CC units were compared with the observed ν(CC) and ν(C―C) band positions of the studied coral and shell. Individual correction factors were used to better match theoretical wavenumbers with observed band positions in red coral and African snail. It was concluded that all‐trans polyene pigments of red coral and dark parts of African snail shell contain 11–12 and 14 CC double bond units, respectively. However, Raman spectroscopy cannot produce any clear information on the presence and nature of the end‐chain substituents in the studied pigments. Copyright © 2016 John Wiley & Sons, Ltd.

Controllable Multicompartmental Capsules with Distinct Cores and Shells for Synergistic Release.

A facile and flexible approach is developed for controllable fabrication of novel multiple-compartmental calcium alginate capsules from all-aqueous droplet templates with combined coextrusion minifluidic devices for isolated coencapsulation and synergistic release of diverse incompatible components. The multicompartmental capsules exhibit distinct compartments, each of which is covered by a distinct part of a heterogeneous shell. The volume and number of multiple compartments can be well-controlled by adjusting flow rates and device numbers for isolated and optimized encapsulation of different components, while the composition of different part of the heterogeneous shell can be individually tailored by changing the composition of droplet template for flexibly tuning the release behavior of each component. Two combined devices are first used to fabricate dual-compartmental capsules and then scaled up to fabricate more complex triple-compartmental capsules for coencapsulation. The synergistic release properties are demonstrated by using dual-compartmental capsules, which contain one-half shell with a constant release rate and the other half shell with a temperature-dependent release rate. Such a heterogeneous shell provides more flexibilities for synergistic release with controllable release sequence and release rates to achieve advanced and optimized synergistic efficacy. The multicompartmental capsules show high potential for applications such as drug codelivery, confined reactions, enzyme immobilizations, and cell cultures.

Ionic Liquid Character of Zinc Chloride Hydrates Define Solvent Characteristics that Afford the Solubility of Cellulose.

The recently described ionic liquid structure of the three equivalent hydrate of zinc chloride (ZnCl2·R H2O, R = 3, existing as [Zn(OH2)6][ZnCl4]) explains the solubility of cellulose in this medium. Only hydrate compositions in the narrow range of 3 - x < R < 3 + x with x ≈ 1 dissolve cellulose. Once dissolved, the cellulose remains in solution up to the R = 9 hydrate. Neutron diffraction and differential pair distribution function analysis of cellulose and model compound solutions (1 wt % cellulose in the R = 3 hydrate and 1 wt % ethanol in the R = 3 hydrate and the ZnCl2·3 ethanol liquid) coupled with detailed solubility measurements suggest that cellulose solubility occurs via coordination of the primary OH to the hydrated zinc cation with ring hydroxyls forming part of a second coordination shell around the cation of the ionic liquid.

Gold core@silver semishell Janus nanoparticles prepared by interfacial etching

Gold core@silver semishell Janus nanoparticles were prepared by chemical etching of Au@Ag core-shell nanoparticles at the air/water interface. Au@Ag core-shell nanoparticles were synthesized by chemical deposition of a silver shell onto gold seed colloids followed by the self-assembly of 1-dodecanethiol onto the nanoparticle surface. The nanoparticles then formed a monolayer on the water surface of a Langmuir-Blodgett trough, and part of the silver shell was selectively etched away by the mixture of hydrogen peroxide and ammonia in the water subphase, where the etching was limited to the side of the nanoparticles that was in direct contact with water. The resulting Janus nanoparticles exhibited an asymmetrical distribution of silver on the surface of the gold cores, as manifested in transmission electron microscopy, UV-vis absorption, and X-ray photoelectron spectroscopy measurements. Interestingly, the Au@Ag semishell Janus nanoparticles exhibited enhanced electrocatalytic activity in oxygen reduction reactions, as compared to their Au@Ag and Ag@Au core-shell counterparts, likely due to a synergistic effect between the gold cores and silver semishells that optimized oxygen binding to the nanoparticle surface.

Infulence of Chemical Composition and Metallographic Structure to Dimagnetic Stainless Steel

A kind of rotating step motor is used in special environment, which has the character of single step angle great,single step rotating speed rangeing widely and output turque rangeing widely. To adapt the using environment and its working characteristics, the motor’s main parts of shell and front-backcovers are all made up of the stainless steel 1Cr18Ni9Ti, which has a good performance in diamagnetic and comperhensive mechanics. During the manufacture process, the 1Cr18Ni9Ti was found can be absorded by magnet. This paper researchs the influence of elements components and metallographic structure to the 1Cr18Ni9Ti by analyzing the element components and metallographic structure of several batches of materials.

Eight years of passive acoustic monitoring in the Alaskan Beaufort Sea: Lessons learned

Every year during open-water season in 2007–2014, up to 40 passive acoustic recorders with directional capability (DASARs) were deployed in the Beaufort Sea, as part of Shell’s Marine Mammal Monitoring and Mitigation Program. The overarching goal of these deployments was to collect information on the effects of industrial operations, such as seismic exploration and drilling activities, on the behavior of bowhead whales during their fall migration. Recorders were placed on the continental shelf at depths of &amp;lt;55 m, offshore of the North Slope of Alaska, between Barter Island and Harrison Bay. Over the eight-year period, more than 3.1 million bowhead calls were localized. Concurrently, various types of industrial sounds were detected and quantified, such as airgun pulses or the tones produced by machinery. Analyses were then performed by matching—for each recorder—the number of calls localized with the amount of industrial sound detected. These analyses have shown that changes in calling behavior happen at low received levels of anthropogenic sound and lead to complex changes in calling behavior, that are governed by received sound levels, but also other factors, such as distance to the industrial activity or type of industrial sound. [Work sponsored by Shell Exploration and Production Company.]

High - Fidelity Reliability Prediction of a Tube Bundle

The reliability of shell and tube heat exchanger is predicted using a 2-stage physics-based simulation. The first stage uses stochastic porous models of the bundle to estimate operational and environmental uncertainties in flow conditions, such as flow velocity and inlet temperature. The results are used for the second stage, which is the CFD simulation of the sub-model. The most critical part of shell and tube heat exchangers is the tube bundle. The technique integrates stochastic fluid-structure interaction with fatigue and Monte Carlo simulations. Heating loads are transferred between models by mapping of actual temperature distributions. A sensitivity analysis is conducted to determine the significant factors that may lead to failure, as it is impractical to consider all input variables. In the sub-model, which is a tube bank, air flow and heat transfer inter-effects between the three tubes and the fins are measured. Thermal stresses are highest at the bonding regions between the water tubes and the fins, and that is because of the high temperature gradient combined with different material properties. Thermal stress in the model is relatively low, however, it has a high effect on fatigue life, and consequently on reliability result. The presented model can be used as a useful tool for reliability-based design of shell and tube heat exchangers.