Three-dimensional Constraints Research Articles

Dynamic mechanical response and crack evolution law of raw coal loaded by dynamic-static coupling under three-dimensional constraints

This paper presents the investigation of the dynamic mechanical properties of coal rock under complex stress conditions at depth, based on the improved Separate Hopkinson Pressure Bar Test System. A total of 15 groups of coal samples were used to perform dynamic impact tests under different conditions. The changing rules of dynamic strength, crushing, fractal dimension and damage modes of coal under different stress conditions were analyzed. A total of nine groups of coal samples were selected for numerical simulation using ANSYS/LS-DYNA. The results show that: (1) The stress–strain curves of coal specimens under different strain rates, different confining pressures and axial pressures have basically the same trend and the curves show a certain jump forward. (2) The peak dynamic stress of the coal specimens increased linearly with the increase of strain rate and confining pressure, and the ambient pressure limited the expansion of internal cracks of the coal specimens under impact loading. Based on the experimental and simulated data, the maximum relative errors between the experimental and simulated data were determined to be 2.9578% for Group A, 6.177% for Group B, and 6.382% for Group C, respectively. (3) The damage modes of the coal samples under the three-dimensional dynamic-static combined loading were mainly “X” type and “conical” shear damage. The fractal dimension increases with the increase of strain rate, decreases with the increase of confining pressure, and first decreases and then increases with the increase of axial pressure. This research achievement can provide theoretical support for the prevention of dynamic disasters in deep coal mine engineering.

Protein Structure-Based Organic Chemistry-Driven Ligand Design from Ultralarge Chemical Spaces.

Ultralarge chemical spaces describing several billion compounds are revolutionizing hit identification in early drug discovery. Because of their size, such chemical spaces cannot be fully enumerated and require ad-hoc computational tools to navigate them and pick potentially interesting hits. We here propose a structure-based approach to ultralarge chemical space screening in which commercial chemical reagents are first docked to the target of interest and then directly connected according to organic chemistry and topological rules, to enumerate drug-like compounds under three-dimensional constraints of the target. When applied to bespoke chemical spaces of different sizes and chemical complexity targeting two receptors of pharmaceutical interest (estrogen β receptor, dopamine D3 receptor), the computational method was able to quickly enumerate hits that were either known ligands (or very close analogs) of targeted receptors as well as chemically novel candidates that could be experimentally confirmed by in vitro binding assays. The proposed approach is generic, can be applied to any docking algorithm, and requires few computational resources to prioritize easily synthesizable hits from billion-sized chemical spaces.

Anti-Penetration Performance of Composite Structures with Metal-Packaged Ceramic Interlayer and UHMWPE Laminate

The impact response of a composite structure consisting of a metal-packaged ceramic interlayer and an ultra-high molecular weight polyethylene (UHMWPE) laminate has been studied through a ballistic test and numerical simulation. The studied structure exhibits 50% higher anti-penetration performance than the traditional ceramic/metal structure with the same areal density. The metal-packaged ceramic interlayer and the UHMWPE laminate are key components in resisting the penetration. By using a metal frame to impose three-dimensional constraints on ceramic tiles, the metal-packaged ceramic interlayer can limit the crushing of the ceramic and contain the broken ceramic fragment to improve the erosion of the projectile. The large deformation of UHMWPE laminate absorbs a large amount of energy from the projectile. By decreasing the amplitude of the shock wave and changing the distribution of the impact load in the structure, the projectile has longer residence time on the interlayer. The anti-penetration performance shows within 10% variation when the impact position is varied. Due to the asymmetric deformation and high elastic recovery ability of the UHMWPE laminate, the projectile trajectory deflection is increased, and the broken ceramic fragments are restrained, thereby mitigating after-effect damage caused by the projectile after penetrating the structure.

Advances in seismic imaging of magma and crystal mush

Seismic imaging methods have provided detailed three-dimensional constraints on the physical properties of magmatic systems leading to invaluable insight into the storage, differentiation and dynamics of magma. These constraints have been crucial to the development of our modern understanding of magmatic systems. However, there are still outstanding knowledge gaps resulting from the challenges inherent in seismic imaging of volcanoes. These challenges stem from the complex physics of wave propagation across highly heterogeneous low-velocity anomalies associated with magma reservoirs. Ray-based seismic imaging methods such as travel-time and surface-wave tomography lead to under-recovery of such velocity anomalies and to under-estimation of melt fractions. This review aims to help the volcanologist to fully utilize the insights gained from seismic imaging and account for the resolution limits. We summarize the advantages and limitations of the most common imaging methods and propose best practices for their implementation and the quantitative interpretation of low-velocity anomalies. We constructed and analysed a database of 277 seismic imaging studies at 78 arc, hotspot and continental rift volcanoes. Each study is accompanied by information about the seismic source, part of the wavefield used, imaging method, any detected low-velocity zones, and estimated melt fraction. Thirty nine studies attempted to estimate melt fractions at 22 different volcanoes. Only five studies have found evidence of melt storage at melt fractions above the critical porosity that separates crystal mush from mobile magma. The median reported melt fraction is 13% suggesting that magma storage is dominated by low-melt fraction crystal mush. However, due to the limits of seismic resolution, the seismological evidence does not rule out the presence of small (<10 km3) and medium-sized (<100 km3) high-melt fraction magma chambers at many of the studied volcanoes. The combination of multiple tomographic imaging methods and the wider adoption of methods that use more of the seismic wavefield than the first arriving travel-times, promise to overcome some of the limitations of seismic tomography and provide more reliable constraints on melt fractions. Wider adoption of these new methods and advances in data collection are needed to enable a revolution in imaging magma reservoirs.

Analytical J-integral model for mode-I cracks in ductile materials with three-dimensional constraints

The J-integral is widely used in fracture analysis to characterize the stress-strain field at the crack tip. To describe the dimensionless relationships between the J-integral and the load for mode-I cracks in ductile materials, a novel model based on the energy density equivalence is proposed by introducing the three-dimensional constraint functions. The model-obtained relationships between the J-integral and the load are shown to be consistent with those obtained via finite element analysis. Moreover, the dimensionless relationships provided by the proposed model are shown to be only related to the constitutive parameters and independent of the geometric dimensions of mode-I cracks.

Quantitative comparisons of depositional architectures of unconfined and confined turbidite sheet systems

Degree of confinement refers to the degree to which sediment gravity flows are influenced by the surrounding basin relief and interact with the basin margins, and is a key controlling factor in determining the depositional architectures of turbidite sheet systems. Two well exposed late Palaeozoic sandy turbidite sheet systems in the Paganzo Basin at Cerro Bola, north-west Argentina, termed Stages II and IV (unconfined and highly confined respectively), provide three-dimensional constraints on facies associations, stacking patterns, depositional geometries and evolution of these turbidite sheet systems. Cluster analysis has been applied to define facies associations in these two systems at an appropriate hierarchical level depending on the overall nature of the system. The overlap index (OI), OI = A0/A1, where A0 is the overlap area and A1 is the area of underlying depositional element, is adopted to quantitatively characterise the stacking patterns. The two turbidite sheet systems show contrasts in that: (1) Stage II is built up by four hierarchical elements, each stacked in a shingled or compensational way with the majority of overlap index values of 0.7 and 0.8, to form higher hierarchical elements, whereas in Stage IV, individual beds stack vertically with OI = 1, together forming the stage and (2) Four facies associations have been identified in Stage II by cluster analysis and they occur in a spatial sequence from axis to fringe; one facies association has been identified in Stage IV and it shows little variation spatially across the basin. In unconfined systems, depositional elements are self-organized, and autocyclic controls are dominant, whereas in highly confined systems, confinement has suppressed the autocyclic signal and systems are allocyclically controlled.

Active disturbance rejection guidance and control scheme for homing missiles with impact angle constraints

An active disturbance rejection guidance and control scheme for homing missiles with three-dimensional impact angle constraints is proposed. The six-degree-of-freedom dynamical and kinematical models containing model uncertainties and disturbances are established. A strict feedback relative dynamics between the target and homing missile in three-dimensional space are deduced. A reconstructed reduced-order attitude controller design model is proposed. A two-loop control structure with respect to the centroid guidance loop and rotational control loop is conducted to implement the six-degree-of-freedom guidance and control system with the help of second-order sliding mode approach and extended state observers. The tracking loop of the Euler angles of the missile can be elided and the number of six-degree-of-freedom control parameters can be reduced. Finally, the effectiveness and robustness of the newly proposed guidance and control scheme are investigated and verified via six-degree-of-freedom nonlinear simulation studies.

Two-dimensional versus three-dimensional constraints in hetero-epitaxy/orientation relationships

Molecular dynamics simulations have been performed to compare the orientation relationships (ORs) that develop between Ag films/particles equilibrated with Ni, depending on whether the Ag is subjected to three-dimensional (3-D) confinement by being embedded in Ni, or to 2-D confinement by equilibration with a Ni substrate. Previous results of both simulations and experiments have shown that Ag films equilibrated with planar Ni substrates display a large number of different ORs; in particular, Ag equilibrated on Ni{100} displays an OR of Ag{111} // Ni{100} , often referred to as an oct-cube OR. Here it is shown that a Ag particle embedded in Ni displays an OR of Ag{111} // Ni{111} , i.e., a cube-on-cube OR. It has also been shown that as the confinement of a Ag particle is gradually increased from 2-D to 3-D, by equilibrating a Ag particle on Ni(100) substrates with progressively deeper dimples, a transition in OR occurs from oct-cube to cube-on-cube. This result contradicts the conventional notion which supposes that the ORs displayed in the presence of 3-D confinement (e.g., during phase transformations) will also tend to be displayed in epitaxy on a substrate.

The Windimurra Igneous Complex: an Archean Bushveld?

Abstract The Archean Windimurra Igneous Complex consists of distinct components, including a thick layered series, with a cumulate mineral stratigraphy similar to the zones identified in the well-studied Bushveld Complex, South Africa. The complex is part of the plume-related and laterally extensive 2.81 Ga Meeline Suite, the intrusive component of a large igneous province. It is an anhydrous tholeiitic suite consisting of five layered mafic–ultramafic intrusions 25–85 km in the long dimension. These intrusions host significant V–Ti mineralization in their fractionated, Fe-rich upper zones. Recent mapping, combined with aeromagnetic, gravity and seismic surveys, has provided unparalleled three-dimensional constraints on the largest of these intrusions. The results of three-dimensional modelling show that it is thicker than previously recognized. At c. 11 km, it is the thickest layered mafic–ultramafic intrusion identified globally and one of the largest such intrusions volumetrically. The mineral zone stratigraphy and many other features associated with this complex share similarities with the c. 800 myr younger Bushveld Complex. On a large scale, three discordant units are delineated geometrically, providing fundamental constraints on a multi-stage genetic model for magma emplacement. The indication of a thick, subsurface Ultramafic Zone provides a potential target for Ni–Cr–platinum group element mineralization.

Fluorine multipolar interaction: Toward elucidating its energetics in binding recognition

Multipolar interactions have gained attention due to their roles in molecular recognition events of chemical and biological systems. Structural evidence suggests that the fluorine multipolar interaction is a favorable molecular interaction in the paradigm of protein-ligand recognition. With an aim to understand its propensity and energetics in ligand-protein assembly, we mined the “Pfizer protein-ligand X-ray structure database” with three-dimensional constraints for the presence of such interactions. A set of transformation rules were applied to generate their corresponding matched molecular pairs (MMPs) that bear hydrogen(s) in place of the interacting fluorine(s). Biological activities were retrieved from our internal data warehouse for the MMPs with and without the ability to form the multipolar interaction. On the basis of the observed potency differences we determined that the free energy gain associated with the fluorine multipolar interaction is relatively modest, ∼0.3–0.6kcal/mol, and the net impact on lipophilic efficiency (LipE) is essentially neutral. A general guideline for medicinal chemists has emerged from this study, enabling a more rational employment of this type of interaction in molecular design.

Neural tube on a chip

Neurodevelopment The information that converts an unruly mob of stem cells into an organized, structured tissue, such as the neural tube, includes diffusible factors and three-dimensional constraints. Demers et al. have now constructed a microfluidics device to deliver morphogens at the right time,

ILP-assisted de novo drug design

De novo design of drugs uses the three-dimensional structure of a target protein (often called the receptor) to design molecules (or ligands) that could bind to the receptor and hence inhibit its functioning. Thus, unlike a ligand-based approach, this form of drug design does not require prior knowledge of inhibitors. In this paper, the three-dimensional structure of a receptor is used indirectly, in the form of molecular interaction fields of the receptor and small molecules (or probes). In addition, we also use domain-specific constraints encoding basic geometric and pharmacological requirements imposed by the target. Interaction energies of one or more targets with a set of probes are used to identify three-dimensional constraints that occur in many--preferably all--targets. In a graph-theoretic sense, the constraints are (small, fixed-size) cliques in graphs with labelled vertices representing probe-specific points of high interaction energy, and edges between a pair of vertices are labelled by the three-dimensional distance between the corresponding points of interaction. Our interest is in the discovery of frequent cliques that satisfy domain-specific constraints. In the paper, the discovery of such patterns is done using an Inductive Logic Programming (ILP) engine. The case for the use of ILP stems primarily from the explicit ways of incorporating domain-constraints, but any other technique capable of discovering frequent cliques from data can be used with some additional effort. The frequent cliques discovered are used to hypothesize pharmacophore-like structures on potential ligands. We test the utility of this approach by conducting a case study on the discovery of anti-malarials. Specifically, we test the approach on proteins belonging to the class of aspartic proteases. We are particularly interested in plasmepsin II, which is an enzyme in the haemoglobin degradation pathway of Plasmodium falciparum. We assess the pharmacophore-like constraints using: (a) a database of known inhibitors and non-inhibitors of aspartic proteases; and (b) a database of decoys that are physico-chemically similar to the aspartic proteases. Our results suggest that the approach could be used to obtain pharmacophores with good precision and recall for aspartic proteases.

Digital development of products with NX9 for academical areas

International competitiveness forced the manufacturing enterprises to look for new ways to accelerate the development of digital products through innovation, global alliances and strategic partnerships. In an environment of global research and development of distributed geographically, all members of the joint teams made up of companies and universities need to access updated and accurate information about products created by any of the type employed, student, teacher. Current design processes involve more complex products consisting of elements of design created by multiple teams, disciplines and suppliers using independent CAD systems. Even when using a 3D CAD mature technology, many companies fail to significantly reduce losses in the process, improve product quality or product type to ensure successful innovations to market arouse interest. These challenges require a radical rethinking of the business model, which belongs to the field of design, which must be based on digital development of products based on integrated files. Through this work, the author has proposed to provide both synthesis and transformations brought news of the integrated NX [1, 2, 3] from Siemens PLM Software 9, following a news results detailed documentary study, and personal results obtained by applying the same version, the digital and integrated development of a product type device test beams. Based on educational license received for NX 9 was made a detailed study of the innovations made by this release, and the application of some of them went to graphical modelling and getting all the documentation of a test device bearing beams. Also, were synthesized in terms of methodology, the steps to take to obtain graphical documentation. The results consist of: 3D models of all parts and assembly 3D model of the three-dimensional constraints of all component parts and not least respectively all drawings and assembly drawing. The most important consequence of the paper is the obtaining of integrated files that can be subjected to further analysis type CAE / CAM / PDM software components by the same company. Additional advantages related files by the synthesis of integrated CAD / CAE / CAM / PDM.

Angle of Attack

Chemistry In qualitative terms, chemists have become adept at predicting how reaction probabilities depend on the relative dispositions of two colliding reagents. For instance, if a reactive site is bounded by a large fragment and a small one, the collision partner is more likely to make it past the small one. This steric effect is the basis for much of asymmetric catalysis. A more detailed, quantitative picture of what happens at any particular collision angle is rather harder to capture. Wang et al. have now mapped out the precise three-dimensional steric constraints guiding an elementary chemical reaction: chlorine's abstraction of a hydrogen atom in the vibrationally excited C-H bond of CHD3 to produce HCl. By varying the polarization of the vibrational excitation laser, the authors could effectively choose the alignment of the (partially deuterated) methane reagent relative to the incoming Cl atom beam, after which they used ion imaging to map out the product trajectories and their associated quantum states. The results for the production of vibrationally relaxed HCl are largely in keeping with expectations from the longstanding line-of-centers model in collision theory, whereas pathways leading to vibrationally excited HCl manifest more complex dynamics. Nat. Chem. 4 , 636 (2012).

One, two and three-dimensional geometric constraints and climatic correlates of North American tree species richness

The 'mid-domain effect' (MDE) has received much attention recently as a candidate explanation for patterns in species richness over large geographic areas. Mid-domain models generate a central peak in richness when species ranges are randomly placed within a bounded geographic area (i.e. the domain). The most common terrestrial mid-domain models published to date have been 1-D latitude or elevation models and 2-D latitude-longitude models. Here, we test 1-D, 2-D and 3-D mid-domain models incorporating latitude, longitude and elevation, and assess independent and concurrent effects of geometric constraints and climatic variables on species richness of North American trees. We use both the traditional 'global' regression models as well as geographically weighted regressions ('local' models) to examine local variation in the contribution of MDE and climatic variables to species richness across the domain. Our results show that in some dimensions the contribution of MDE to patterns of species richness can be quite substantial, and we show that in most cases a combination of MDE and climate predicted empirical species richness best in both local and global models. For the North American domain, MDE in the elevation dimension is clearly important in describing patterns of empirical species richness. We also show that the assumption of stationarity in global models is not met in the North American domain and that results of these models mask complex patterns in both the effect of MDE on richness and the response of species richness to climate. In particular we show the increased explanatory role of MDE in predicting species richness as domain edges are approached. Our results support the hypothesis that geometric constraints contribute to species richness patterns and we suggest the mid-domain effect should be considered alongside more traditional environmental correlates in understanding patterns of species diversity.

Situation Displays for Dynamic UAV Replanning: Intuitions and Performance for Display Formats

Operating unmanned aerial vehicles (UAVs) requires quickly replanning routes to satisfy multiple complex three-dimensional (3D) mission constraints. How well do conventional two-dimensional (2D) displays support replanning? What are users' intuitions about alternate display formats, given the trend towards user-configured displays? Previously, we developed a realistic replanning task, and measured time and accuracy for satisfying UAV mission constraints. With present-day 2D displays, performance was particularly poor in complex mountainous environments (Cook, Smallman, Lacson, & Manes, 2009). In the current work, to address this shortfall, we designed novel displays to support replanning, and measured performance and intuitions for three canonical display formats: (1) baseline 2D, a proxy for current UAV displays, (2) augmented 2D, with integrated replanning constraints, and (3) perspective 3D, comparable in features to the augmented 2D. Using the three formats, participants replanned UAV routes compromised by closed airspace and repositioned ISR targets, over flat and mountainous terrain. Replanning was slowest and most error-prone for baseline 2D in flat terrain, and error severity was greatest for perspective 3D in mountainous terrain. However, users' intuitions strongly favored perspective 3D. Overall, time and accuracy were best for augmented 2D, and better performance with augmented 2D relied less upon higher spatial ability. Results highlight the mismatch of users' intuitions with performance, and the role of individual differences. The study informs the design of future replanning displays and lays the foundation for introducing and visualizing automated path planning solutions.

505 非一般化座標を用いた大変形マルチボディシステムの汎用3次元ジョイント拘束(ジョイントのモデリングとその応用,OS-19 マルチボディダイナミクス,総合テーマ「伝統を,未来へ!」)

505 非一般化座標を用いた大変形マルチボディシステムの汎用3次元ジョイント拘束(ジョイントのモデリングとその応用,OS-19 マルチボディダイナミクス,総合テーマ「伝統を,未来へ!」)

Surface-Immobilized Peptide Aptamers as Probe Molecules for Protein Detection

We demonstrate the use of surface-immobilized, oriented peptide aptamers for the detection of specific target proteins from complex biological solutions. These peptide aptamers are target-specific peptides expressed within a protein scaffold engineered from the human protease inhibitor stefin A. The scaffold provides stability to the inserted peptides and increases their binding affinity owing to the resulting three-dimensional constraints. A unique cysteine residue was introduced into the protein scaffold to allow orientation-specific surface immobilization of the peptide aptamer and to ensure exposure of the binding site to the target solution. Using dual-polarization interferometry, we demonstrate a strong relationship between binding affinity and aptamer orientation and determine the affinity constant KD for the interaction between an oriented peptide aptamer ST(cys+)_(pep9) and the target protein CDK2. Further, we demonstrate the high selectivity of the peptide aptamer STM_(pep9) by exposing surface-immobilized ST(cys+)_(pep9) to a complex biological solution containing small concentrations of the target protein CDK2.

Regulation of axon guidance and extension by three-dimensional constraints

Axons in vivo are guided by molecular signals acting as attractants and repellents, and possibly by physical constraints encountered in the extracellular environment. We analyzed the ability of primary sensory axons to extend and undergo guidance in three-dimensional (3-D) environments generated using photolithography. Confinement of neurons in fully enclosed square chambers decreased the percentage of neurons establishing axons as a function of chamber width. However, the ability to extend an axon in one or more directions allowed axons to form and extend similarly to those on two-dimensional (2-D) substrata. Live imaging of growth cones interacting with the walls of chambers or corridors revealed that growth cones respond to contact with a 3-D constraint by decreasing surface area, and circumvent constraints by repeated sampling of the constraint until an unobstructed path is encountered. Analysis of the ability of axons to turn around corners in corridors revealed that the angle of the corner and corridor width determined the frequency of turning. Finally, we show that the length of axons can be controlled through the use of 3-D constraints. These data demonstrate that 3-D constraints can be used to guide axons, and control the extent of axon formation and the length of axons.

The effect of screening of the magnetotelluric field by high resistivity layers: Three-dimensional numerical modeling constraints

A 3-D numerical modeling approach is applied to the effect of screening of the magnetotelluric (MT) field by high resistance (≥106 Ω m2) layers, which up to now has mainly been studied in terms of 2-D heterogeneous models of geological sections [Berdichevsky and Yakovlev, 1990]. Three-layer models above a poorly conducting basement (ρ=104 Ω m) are used. The resistance of the screening layer was generally taken equal to 2×106 Ω m2 and its thickness was varied from 200 to 2000 m. The resistivity of the host medium was set at 10 Ω m. Heterogeneities of a low and a high resistivity (ρ=10−3 and 104 Ω m, respectively) ranging in horizontal size from 4 to 40 km and having a height of 1–2.8 km (a protrusion on the basement) were examined. Based on calculations of these models, 2-D and 3-D screening effects were compared. The 3-D modeling determined values of model parameters at which the screening properties are preserved both in the case of a screen of limited horizontal dimensions and in the presence of a rupture in the screen comparable in horizontal size with the 3-D heterogeneity. As follows from the modeling results, the screening effect of the high resistivity model layers seriously complicates the use of MT soundings for the identification of a local heterogeneity of both a low and a high resistivity (ρ=10−3 and 104 Ω m, respectively) if its lateral size is smaller than the 4-km thickness of the studied three-layer section in question and its height is 1–1.5 km. The regular patterns of the screening effect revealed in this work are of interest in electromagnetic sounding applications.