Ordinary Arc Research Articles

Early zircon saturation in adakitic magmatic differentiation series and low Zr content of porphyry copper magmas

Porphyry copper ore-forming magmas worldwide are chemically distinguished from ordinary arc granitoids by lower Zr and by higher Sr/Zr ratios at equivalent SiO2 contents. Low ppm Zr in zircon-saturated melts and high whole-rock Sr/Zr in granitoid samples retaining igneous plagioclase are useful discriminants of Cu-fertile intrusive complexes. These and other chemical discriminants of porphyry-copper-forming melts of tonalite-granodiorite-adamellite composition cannot develop during crystallisation-differentiation at upper-crustal pressures. They indicate unusually high dissolved H2O (≥ 9 wt%) in residual melts at depths near the base of the crust. We compare Zr behaviour during mafic-to-felsic magmatic differentiation in orogenically deforming, copper-mineralised arc segments with behaviour during differentiation in non-orogenic, unmineralised arc segments laterally adjacent along the same subduction zones. In orogenically deforming segments, horizontal compressive stress provides resistance to opening of tensile dyke fractures and promotes entrapment of mantle-derived basaltic melts in magma chambers embedded in hot country rock at Moho-vicinity depths, where magmas cool slowly and residual melts tend to last long enough to experience intermittent chamber replenishment by basaltic melts from the deeper mantle. Over several cycles of replenishment and fractional crystallisation, residual melts acquire high concentrations of inherited chemical components that were largely excluded from cumulus minerals—H2O, Cl, CO2, SO3, etc. Accumulating H2O re-orders the high-pressure crystallisation sequence of igneous minerals in successive cycles and leads to early and prolific production of hornblende and early zircon saturation in mafic melts (< 60 wt% SiO2) of later cycles and leads to low Zr contents of zircon-saturated intermediate-composition residual melts.

St. Francis, and: Arctic Palimpsest, and: Nocturne at Midnight

St. Francis, and: Arctic Palimpsest, and: Nocturne at Midnight Mary Lee (bio) In my dreams, St. Francisspeaks in the field of me, and his sparrows gather nearto listen. St. Francis of pain’s unfadingcenter, what brightly hums as a thrummed pulse of bees,I know how it turns a mouth silent. Muted,the mouth’s O most adjacent to the blottediris-ring found on poppies. The aperture of lack’s taste,language made inadequate. Is it true that there is a soundto speech leaving you. To be still and knowthe morning with its choir of trees alive in me, hiddenbetween grasses, lilies, wordless stones in the passingof hours as somewhere I can hear the face of the impossible moonfalling clear over pools of water. [End Page 37] Arctic Palimpsest When God painted my doe face,he must have added a dab of rougeand a streak of oblivion. How could Ihave known the exact shape of my lifeobscured by leaves, capable as any eye’s flicker?In the forest, I was another absence—a doe wanting to turn real in the shade,always a little lost in the landscape.My breath left no consequence in the air.Despair was the larger animal I couldn’t see,readying awake while I remained sleeping.And when despair, the animal, rearedits restless head—a remnant of its kisslike a thorn lodged into the side of my flesh.Then I saw what seemed like the wrist of God,his back retreating into the shadows,and briefly, the light was a stillness in medrawn over the face of the world. ________ In the mind of a doe, more and more snow.Across endless snow, a mind blank to fill.Sometimes it beckons and withoutquestion I follow its uncertain forms—like the footprints of a doe leading me furtherand further out across snow until I am the snow.Or were the footprints my own? Was I the doewith a mind sewn closed by the cold,unable to see the cold as separatefrom myself? Sometimes in the privacyof my own sadness I feel like a thing hunted.Sometimes when I imagine the sadness,I think the sadness imagines me. [End Page 38] ________ The deer are braver in the cold than youcould ever be, their hooves kissing the whitelandscape in a lattice. Alreadythe fresh snow comes to fill those markswhere their weight pressed in. You can imaginetheir deer lungs calming as they watch the sundisappear inside the growing dark,their heads nodding awake at dawn,ears twitching as the hares stiramong the nearby grasses. Some of the deer,startled, bound past the trees,their glassy eyes quivering,traces of a dream. And the ones fallen over,sides opened and ears splayedon the ground, their blood spilling outas they listen to ice expanding below,loud cracks echoing like the soundof a troop of whales coming to save them—Their breath hangs there for a while.You can almost see it there still. [End Page 39] Nocturne at Midnight Maybe a stone had pierced the glass, a boy’s stoneof hatred or love puncturing the window in an ordinary arc—Or maybe the sharp end of a nearby branchhad been driven into the glass during a storm,fractures spreading out like veinsaround the point where it struck. Whatever it wasmade no difference. There was the windowwith a hole the size of her eye that might fit a key,a small opening for her to peer through, to see,on the other side, the yard’s lengthening shadows.Only night, that dark pitch of wine, like some brutalsweetness filling one’s animal mouth in a thicketof blackberries. As if, in the middle of the night, too muchpours into the mind, assembles as a nocturne of starlings—But there was light, wasn’t there? There was a candleheld up against the panes, and her mind to transformthe overwhelm of night. To imagine night blossomingalong the bare arms of trees that could...

Snake Graphs from Triangulated Orbifolds

We give an explicit combinatorial formula for the Laurent expansion of any arc or closed curve on an unpunctured triangulated orbifold. We do this by extending the snake graph construction of Musiker, Schiffler, and Williams to unpunctured orbifolds. In the case of an ordinary arc, this gives a combinatorial proof of positivity to the generalized cluster algebra from this orbifold.

Network Model for the Problem of Integer Balancing of a Four-Dimensional Matrix

The problem of integer balancing of a four-dimensional matrix is studied. The elements of the inner part (all four indices are greater than zero) of the given real matrix are summed in each direction and each two- and three-dimensional section of the matrix; the total sum is also found. These sums are placed into the elements where one or more indices are equal to zero (according to the summing directions). The problem is to find an integer matrix of the same structure, which can be produced from the initial one by replacing the elements with the largest previous or the smallest following integer. At the same time, the element with four zero indices should be produced with standard rules of rounding-off. In the article the problem of finding the maximum multiple flow in the network of any natural multiplicity k is also studied. There are arcs of three types: ordinary arcs, multiple arcs and multi-arcs. Each multiple and multi-arc is a union of k linked arcs, which are adjusted with each other. The network constructing rules are described. The definitions of a divisible network and some associated subjects are stated. There are defined the basic principles for reducing the integer balancing problem of an l-dimensional matrix (l ≥ 3) to the problem of finding the maximum flow in a divisible multiple network of multiplicity k. There are stated the rules for reducing the four-dimensional balancing problem to the maximum flow problem in the network of multiplicity 5. The algorithm of finding the maximum flow, which meets the solvability conditions for the integer balancing problem, is formulated for such a network.

An evolutionary keyhole-mode heat transfer model in continuous plasma arc welding

Keyhole plasma arc welding is superior to other ordinary arc welding technologies in deep penetration welding. Energy can be transferred to bottom metal by hot plasma arc in keyhole rather than merely by heat conduction through whole thickness. Hence, an evolutionary keyhole-mode heat transfer model was developed to demonstrate this thermo-physical process. In view of the relative movement of plasma torch and workpiece, a double-elliptical heat source was set up on top surface and a developing conical heat source below, which is closely related to keyhole depth by Volume of Fluid method. Based on analogy to practical welding process, a dynamic energy distribution coefficient was established and an adjustment factor was introduced to account for pressure variation. According to numerical simulation, evolutionary energy propagation process, corresponding temperature field and molten pool geometry were demonstrated simultaneously. The dynamical keyholing process and the consequent keyhole-mode heat transfer and fluid flow were revealed in continuous keyhole plasma arc welding. Experiment was conducted on an 8 mm-thick stainless steel plate, and the measured weld geometry, keyhole size and keyhole exit deviation show reasonable agreement with calculated results.

The problem of finding the maximum multiple flow in the divisible network and its special cases

In the article the problem of finding the maximum multiple flow in the network of any natural multiplicity k is studied. There are arcs of three types: ordinary arcs, multiple arcs and multi-arcs. Each multiple and multi-arc is a union of k linked arcs, which are adjusted with each other. The network constructing rules are described. The definitions of a divisible network and some associated subjects are stated. The important property of the divisible network is that every divisible network can be partitioned into k parts, which are adjusted on the linked arcs of each multiple and multi-arc. Each part is the ordinary transportation network. The main results of the article are the following subclasses of the problem of finding the maximum multiple flow in the divisible network. 1. The divisible networks with the multi-arc constraints. Assume that only one vertex is the ending vertex for a multi-arc in s network parts. In this case the problem can be solved in a polynomial time. 2. The divisible networks with the weak multi-arc constraints. Assume that only one vertex is the ending vertex for a multi-arc in k-1 network parts (1 ≤ s < k − 1) and other parts have at least two such vertices. In that case the multiplicity of the maximum multiple flow problem can be decreased to k - s. 3. The divisible network of the parallel structure. Assume that the divisible network component, which consists of all multiple arcs, can be partitioned into subcomponents, each of them containing exactly one vertex-beginning of a multi-arc. Suppose that intersection of each pair of subcomponents is the only vertex-network source x0. If k=2, the maximum flow problem can be solved in a polynomial time. If k ≥ 3, the problem is NP-complete. The algorithms for each polynomial subclass are suggested. Also, the multiplicity decreasing algorithm for the divisible network with weak multi-arc constraints is formulated.

Network Model for The Problem of Integer Balancing of a Fourdimensional Matrix

The problem of integer balancing of a four-dimensional matrix is studied. The elements of the inner part (all four indices are greater than zero) of the given real matrix are summed in each direction and each two- and three-dimensional section of the matrix; the total sum is also found. These sums are placed into the elements where one or more indices are equal to zero (according to the summing directions). The problem is to find an integer matrix of the same structure, which can be produced from the initial one by replacing the elements with the largest previous or the smallest following integer. At the same time, the element with four zero indices should be produced with standard rules of rounding - off. In the article the problem of finding the maximum multiple flow in the network of any natural multiplicity is also studied. There are arcs of three types: ordinary arcs, multiple arcs and multi-arcs. Each multiple and multi-arc is a union of linked arcs, which are adjusted with each other. The network constructing rules are described. The definitions of a divisible network and some associated subjects are stated. There are defined the basic principles for reducing the integer balancing problem of an -dimensional matrix ( ) to the problem of finding the maximum flow in a divisible multiple network of multiplicity . There are stated the rules for reducing the four-dimensional balancing problem to the maximum flow problem in the network of multiplicity 5. The algorithm of finding the maximum flow, which meets the solvability conditions for the integer balancing problem, is formulated for such a network.

The Problem of Finding the Maximal Multiple Flow in the Divisible Network and its Special Cases

In the article the problem of finding the maximal multiple flow in the network of any natural multiplicity k is studied. There are arcs of three types: ordinary arcs, multiple arcs and multi-arcs. Each multiple and multi-arc is a union of k linked arcs, which are adjusted with each other. The network constructing rules are described. The definitions of a divisible network and some associated subjects are stated. The important property of the divisible network is that every divisible network can be partitioned into k parts, which are adjusted on the linked arcs of each multiple and multi-arc. Each part is the ordinary transportation network. The main results of the article are the following subclasses of the problem of finding the maximal multiple flow in the divisible network. 1. The divisible networks with the multi-arc constraints. Assume that only one vertex is the ending vertex for a multi-arc in k −1 network parts. In this case the problem can be solved in a polynomial time. 2. The divisible networks with the weak multi-arc constraints. Assume that only one vertex is the ending vertex for a multi-arc in s network parts (1 ≤ s < k − 1) and other parts have at least two such vertices. In that case the multiplicity of the multiple flow problem can be decreased to k − s. 3. The divisible network of the parallel structure. Assume that the divisible network component, which consists of all multiple arcs, can be partitioned into subcomponents, each of them containing exactly one vertex-beginning of a multi-arc. Suppose that intersection of each pair of subcomponents is the only vertex-network source x0. If k = 2, the maximal flow problem can be solved in a polynomial time. If k ≥ 3, the problem is NP-complete. The algorithms for each polynomial subclass are suggested. Also, the multiplicity decreasing algorithm for the divisible network with weak multi-arc constraints is formulated.

Geochemical fingerprint of the primary magma composition in the marine tephras originated from the Baegdusan and Ulleung volcanoes

The intraplate Baegdusan (Changbai) and Ulleung volcanoes located on the border of China, North Korea, and East/Japan Sea, respectively, have been explained by appeals to both hotspots and asthenospheric mantle upwelling (wet plume) caused by the stagnant Pacific plate. To understand the origin of the Baegdusan and Ulleung volcanism, we performed geochemical analyses on the tephra deposits in the East/Japan Sea basins originating from the Baegdusan and Ulleung volcanoes. The volcanic glass in the tephra from the Baegdusan and Ulleung volcanoes ranged from alkaline trachyte to peralkaline rhyolite and from phonolite to trachyte, respectively. The tephra from the two intraplate volcanoes showed highly enriched incompatible elements, such as Tb, Nb, Hf, and Ta, distinct from those of the ordinary arc volcanoes of the Japanese islands. The straddle distribution of the Th/Yb and Ta/Yb ratios of the tephra deposits from the Baegdusan volcano may originate from the alkali basaltic magma resulting from mixing between the wet plume from the stagnant Pacific plate in the transition zone and the overlying shallow asthenospheric mantle. In contrast, the deposits from the Ulleung volcano show a minor contribution of the stagnant slab to the basaltic magma, implying either partial melting of a more enriched mantle, smaller degrees of partial melting of a garnet-bearing mantle source, or a combination of both processes as the magma genesis. Our study indicated that the Baegdusan and Ulleung volcanoes have different magma sources and evolutionary histories.

The Resulting Toolpath of Turning a Special Surface on CNC Lathe

The surface of workpiece in NC turning process, often encounter the workpiece surface cross quadrant arc, if the use of the same processing methods and ordinary arc, often leads to the emergence of cross quadrant arc machining shape error, through the research of the NC machining of workpiece surface cross quadrant arc, CNC turning reasonable go knife and tool path in NC turning, solve cross quadrant arc, some defects in the surface of the workpiece processing, ensure the machining with circular arc profile theory demands, so as to improve the machining quality and the machining accuracy requirements.

Horizontal welding of aluminium alloys by soft plasma arc

Horizontal welding plays an important role in manufacture of large and heavy aluminium alloy structures. But there are many problems such as bad weld formation, porosity and low efficiency. Variable polarity plasma arc welding is a low-defect and high-efficiency welding technology, but it has difficulty in horizontal position. The maximum weldable thickness is less than 6.4 mm in single-pass weld. The soft plasma arc was proposed in this article. Horizontal welding of aluminium alloy plates with 8 mm thickness was realized successfully. The joint was free of defects and had excellent mechanical properties. This is a breakthrough in single-pass horizontal welding. Moreover, the characteristic of the soft plasma arc was studied in detail and the fluid flow in weld backside was observed. Finally, the forming mechanism of a stale weld pool was discussed. Results indicated that the arc pressure with the soft plasma arc was lower than that with the ordinary plasma arc. The fluid flow was asymmetric in horizontal position. The forming of a keyhole was realized by the bridging of the molten metals in the upper and lower sides. The weld pool was stable with the soft plasma arc because the maximum diameter of keyhole was bigger than that with the ordinary plasma arc.

Research on Twin-Arc TIG Welding with Ultrasonic Excitation and Its Effect to Weld

. In order to enhance the mechanical properties of weld by using ultrasonic vibration, a new method of twin-arc TIG welding was developed. The welding will be completed by jointly using combined ultrasonic arc and ordinary DC arc technology. The ultrasonic arc was used for injecting ultrasound excitation into the molten pool to improve weld quality, and the DC arc was used as main heat source to increase deposition efficiency. The feasibility experiment of the welding system was done by using the steel 304. Metallographic analysis shows that the method can thin the microstructure of weld. The tensile testing under nature temperature indicates that the method can improve tensile properties of the weld effectively.

Siphon-Based Deadlock Prevention Policy for Flexible Manufacturing Systems

A siphon-based algorithm for deadlock prevention of a type of Petri nets called S3PMR, which is a subclass of S3PGR2, is presented in this correspondence. The proposed method is an iterative approach by adding two kinds of control places called ordinary control (OC) places and weighted control (WC) places to the original model to prevent siphons from being unmarked. An OC place with ordinary arcs, which optimally prevent a siphon from becoming unmarked, is employed whenever it is possible, and otherwise, the WC places that adopt a conservative policy of controlling the release of parts into the system are used. Furthermore, this algorithm is not only for the subclass Petri nets but also for S3PR, ES 3PR, S2LSPR, and S3PGR2 nets. The authors prove the liveness and reversibility of the controlled net, and hence establish the correctness of the deadlock prevention policy. Finally, numerical experiments indicate that the proposed policy appears to be more permissive than closely related approaches in the literature

Facets of the polytope of the asymmetric travelling salesman problem with replenishment arcs

The Asymmetric Travelling Salesman Problem with Replenishment Arcs (RATSP) is a new class of problems arising from work related to aircraft routing. Given a digraph with cost on the arcs, a solution of the RATSP, like that of the Asymmetric Travelling Salesman Problem, induces a directed tour in the graph which minimises total cost. However the tour must satisfy additional constraints: the arc set is partitioned into replenishment arcs and ordinary arcs, each node has a non-negative weight associated with it, and the tour cannot accumulate more than some weight limit before a replenishment arc must be used. To enforce this requirement, constraints are needed. We refer to these as replenishment constraints. In this paper, we review previous polyhedral results for the RATSP and related problems, then prove that two classes of constraints developed in V. Mak and N. Boland [Polyhedral results and exact algorithms for the asymmetric travelling salesman problem with replenishment arcs, Technical Report TR M05/03, School of Information Technology, Deakin University, 2005] are, under appropriate conditions, facet-defining for the RATS polytope.

Mechanical Behaviour of Joints in FSW: Residual Stress, Inherent Strain and Heat Input Generated by Friction Stir Welding

For ordinary arc welding processes such as MIG, welding deformation, residual stress and inherent strain are important factors to control the reliability of weldments. Friction stir welding (FSW) is a new welding method, especially for light metals. The distortion of FSW is reportedly small but reasons can not be determined in detail. This paper deals with thermal cycles and inherent strains which create both residual stresses and welding deformations, in order to make clear effective factors that lower apparent strains on FSW than on MIG. Inherent strains were measured by using the layer removal technique. Thermal cycles and maximum temperature rise were measured by type K thermocouples. It is concluded from experimental data that the main cause lowering apparent strain in FSW is the compressive load that makes tensile plastic strain in weldments. The second cause is that the heat input is smaller than in ordinary arc welding processes.

Synthesis and characterization of cobalt nanoparticles encapsulated in boron nitride nanocages

Abstract A large quantity of boron nitride (BN) nanocapsules with cobalt nanoparticles were fabricated by nitridation of boron and cobalt nanoparticles with a H2/NH3 gas mixture. High-resolution electron microscopy showed that cobalt nanoparticles were encapsulated by boron nitride layers with thickness of ∼5 nm. Magnetization and photoluminescence measurements of the BN nanocapsules showed ferromagnetism and luminescence at 3.8 eV, which would be due to separation of Co nanoparticles by the BN layers. The present work indicates that the nitridation of boron particles with catalytic metal is a useful fabrication method for mass production of BN nanocapsules at low temperatures compared to the ordinary arc discharge method.

Chemical synthesis of silver nanoparticles encapsulated in boron nitride nanocages

Silver nanoparticles encapsulated within boron nitride nanocages were produced from mixtures of boric acid, urea and silver nitrate upon reduction at 700 °C in hydrogen; this is a useful fabrication method for the mass production of boron nitride nanocapsules at low temperatures compared to the ordinary arc discharge method.

Formation and structure of carbon nanocage structures produced by polymer pyrolysis and electron-beam irradiation

Carbon nanocapsules with SiC and Au nanoparticles were produced by thermal decomposition of polyvinyl alcohol at about 500 °C in Ar gas atmosphere. The formation mechanism of nanocapsules and a structural model for the nanocapsule/SiC interface were proposed. In addition, carbon clusters were formed at the surface of carbon nanocapsules, and carbon onions were produced by electron irradiation of amorphous carbon produced from polyvinyl alcohol. The present work indicates that the pyrolysis of polymer materials with clusters is a useful fabrication method for the mass production of carbon nanocapsules and onions at low temperatures compared to the ordinary arc discharge method.

Formation of carbon nanocapsules with SiC nanoparticles prepared by polymer pyrolysis

Carbon nanocapsules with SiC nanoparticles were produced by thermal decomposition of polyvinyl alcohol with SiC clusters at 500 °C in Ar gas atmosphere. High-resolution electron microscopy also showed the formation of carbon hollow structures such as nanoparticles, polyhedra, and clusters. The present work indicates that the pyrolysis of polymer materials with clusters is a useful fabrication method for the mass-production of carbon nanocapsules at low temperatures compared to the ordinary arc discharge method.

伊豆・小笠原，マリアナ前弧の蛇紋岩海山 潜水調査船による観察と陸上蛇紋岩帯との関連

Serpentine seamount was reviewed with recent seven Shinkai 6, 500 dives at Izu-Bonin and Mariana forearcs. The seamounts consist mostly of serpentine flows with huge xenoliths of peridotite, high-pressure type metamorphic rocks such as jadeite-quartz assemblage and aragonite, glaucophane schist as well as MORB like basaltic rocks and chert. Active seamount has the following three characteristic features ; 1) serpentine flow, 2) carbonate chimney, and 3) huge peridotite xenolith in the flow. Serpentine flow shows a lobate structure with several meters width and 2-3 m high, sometimes flows down along the steep cliff. Drilling results indicate that flow unit shows the sedimentary structure similar to the interior structure of the mud diapir. Carbonate chimneys exist as an isolated tree and more than 20 chimneys stand make a line in some cases. Active carbonate chimney has yellowish green bacterial mats on the surface but dead ones are covered with thin black manganese coating. The fate of carbonate chimneys is fell down and dissolves into the sea water when the depth exceeds more than 4, 000 m, becomes a member of sediments when buried and sometimes makes a vein.In the metamorphic belts onland such as Sanbagawa, Kamuikotan metamorphic terrains and Mineoka belt there are serpentinite bodies of both alpine and stratiform types. The former type was thought to be of solid intrusion along fault. These serpentinite bodies yield white sediments as a vein, layer of sediments as well as rodingites. Rodingites always crop out with serpentinites in the Alps and other orogenic belts. Serpentinite bodies have highly sheared and brecciated parts and most geologists thought those parts to be the results of strong shearing when solid intrusion. However, if we look at the body carefully, sedimentary structure and white veins, and sediments will be frequently observed and the body is closely accompanied by rodingites.We strongly insist to think that these white materials are the products of the carbonate chimneys and sedimentary structures are also the product of serpentine flow at the forearc serpentine seamount and emplace into the metamorphic terrains during the secondary processes. During the emplacement, rodingite and magnesite ore would be formed by metasomatism with serpentinites.Most of the serpentinites in the orogenic belt must be of serpentine seamount origin such as in Izu-Bonin, Mariana, Tonga and Middle America Trenches where the crust are thin compared with those of the ordinary island arcs and continental margins.