Triangular Fibrocartilage Complex MR Imaging
Directory of Open Access Journals (Sweden)
Seyed Hassan Mostafavi
2010-05-01
Full Text Available Interpretation of MR imaging of the wrist may be difficult because of the small size of this joint, its complex anatomy, and its sometimes poorly unders-tood pathologic lesions. A recent study revealed that MR imaging of the wrist influences clinicians' diagnoses and management plans in most patients. "nWhich structures make up the triangular fibrocarti-lage complex (TFCC are not universally agreed upon. In most descriptions, however, the TFCC is composed of the triangular fibrocartilage (TFC, the meniscus homolog, the ulnar collateral ligament, the dorsal and volar radioulnar ligaments and the sheath of the extensor carpi ulnaris tendon. The ulnolunate and ulnotriquetral ligaments may also be considered as part of the TFCC. These structures are a complex unit that function as a stabilizing element in the pivot movement of the radius and ulna and limit the lateral deviation of the carpus. The distal radioulnar joint is primarily stabilized by the TFCC. The TFC functions as a cushion between the ulnar head and carpal bones. Many of the structures that make up the complex are connected by fibrous bands. "nThis presentation summarizes the current diagnostic criteria that can be useful in interpreting abnormalities of the triangular fibrocartilage complex (TFCC of the wrist in this difficult topic in joint MR imaging
Uranium (VI)Bis(imido) chalcogenate complexes:synthesis and density functional theory analysis
Energy Technology Data Exchange (ETDEWEB)
Spencer, Liam P [Los Alamos National Laboratory; Batista, Enrique R [Los Alamos National Laboratory; Boncella, James M [Los Alamos National Laboratory; Yang, Ping [Los Alamos National Laboratory; Scott, Brian L [Los Alamos National Laboratory
2009-01-01
Bis(imido) uranium(VI) trans- and cis-dichalcogenate complexes with the general formula U(NtBu)2(EAr)2(OPPh3)2 (EAr = O-2-tBuC6H4, SPh, SePh, TePh) and U(NtBu)2(EAr)2(R2bpy) (EAr = SPh, SePh, TePh) (R2bpy = 4,4'-disubstituted-2,2'-bipyridyl, R = Me, tBu) have been prepared. This family of complexes includes the first reported monodentate selenolate and tellurolate complexes of uranium(VI). Density functional theory calculations show that covalent interactions in the U-E bond increase in the trans-dichalcogenate series U(NtBu)2(EAr)2(OPPh3)2 as the size of the chalcogenate donor increases and that both 5f and 6d orbital participation is important in the M-E bonds of U-S, U-Se, and U-Te complexes.
Uranium (VI)Bis(imido) chalcogenate complexes:synthesis and density functional theory analysis
International Nuclear Information System (INIS)
Bis(imido) uranium(VI) trans- and cis-dichalcogenate complexes with the general formula U(NtBu)2(EAr)2(OPPh3)2 (EAr = O-2-tBuC6H4, SPh, SePh, TePh) and U(NtBu)2(EAr)2(R2bpy) (EAr = SPh, SePh, TePh) (R2bpy = 4,4'-disubstituted-2,2'-bipyridyl, R = Me, tBu) have been prepared. This family of complexes includes the first reported monodentate selenolate and tellurolate complexes of uranium(VI). Density functional theory calculations show that covalent interactions in the U-E bond increase in the trans-dichalcogenate series U(NtBu)2(EAr)2(OPPh3)2 as the size of the chalcogenate donor increases and that both 5f and 6d orbital participation is important in the M-E bonds of U-S, U-Se, and U-Te complexes.
Chalcogenated Schiff bases: Complexation with palladium(II) and Suzuki coupling reactions
Indian Academy of Sciences (India)
Pradhumn Singh; G K Rao; Mohd Salman Karim; Ajai K Singh
2012-11-01
Chalcogenated Schiff bases of 5-chloroisatin (L1-L3), 2-(methythio)benzaldehyde (L4), 2-acetylpyridine (L5) and benzaldehyde (L6-L7) have been synthesized. Both the carbonyl groups of 5- chloroisatin appear to be reactive (noticed for the first time) for making >C=N bond, of course one at a time only. The 1H, 13C{1H}, 77Se{1H} and 125Te{1H} NMR spectroscopy have been used to establish the coexistence of two products, which were found in the ratio 53:47 (E = S), 55:45 (E = Se) and 81:19 (E = Te). The larger amount is of the one in which C=O group away from NH is derivatized. The two products are not separable. Palladium complexes (1-4) of Schiff bases of other three aldehydes were synthesized. The ligands as well as complexes were characterized by multinuclear NMR spectroscopy. The crystal structures of [Pd(L4/L5)Cl][ClO4] (1/2) have been solved. The Pd-Se bond lengths are 2.4172(17) and 2.3675(4) Å, respectively for 1 and 2. The Pd-complexes (3-4) of L6-L7 were explored for Suzuki-Miyaura coupling and found promising as 0.006 mol % of 3 is sufficient to obtain good conversion with TON up to 1.58 × 104.
Coordination field analysis of rare earth complexes with triangular symmetry
Institute of Scientific and Technical Information of China (English)
范英芳; 潘大丰; 杨频
1997-01-01
The calculation of the complex matrixes in odd triangular symmetry was accomplished.The configurations of the coordination unit with various triangular symmetries and different ligand numbers were discussed.On the basis of the double-sphere coordination point-charge (DSCPCF) model,the detailed forms of the DSCPCF parameters Bmk and the expressions of the perturbation matrix elements in triangular field (D3,D3h,D3d) were derived.Thereby,the calculation scheme of coordination field perturbation energy of the rare earth complexes with triangular symmetry was constructed After the calculation scheme was programmed,the Stark energies of the crystalline TbAl3(BO3)4 were calculated The results were considerably close to the experimental values
Zhao, Qiang
2014-10-01
The interplay between halogen and chalcogen bonding in the XCl∙∙∙OCS and XCl∙∙∙OCS∙∙∙NH3 (X = F, OH, NC, CN, and FCC) complex was studied at the MP2/6-311++G(d,p) computational level. Cooperative effect is observed when halogen and chalcogen bonding coexist in the same complex. The effect is studied by means of binding distance, interaction energy, and cooperative energy. Molecular electrostatic potential calculation reveals the electrostatic nature of the interactions. Cooperative effect is explained by the difference of the electron density. Second-order stabilization energy was calculated to study the orbital interaction in the complex. Atoms in molecules analysis was performed to analyze the enhancement of the electron density in the bond critical point.
Majumdar, Subhojit; Stauber, Julia M; Palluccio, Taryn D; Cai, Xiaochen; Velian, Alexandra; Rybak-Akimova, Elena V; Temprado, Manuel; Captain, Burjor; Cummins, Christopher C; Hoff, Carl D
2014-10-20
The enthalpy of oxygen atom transfer (OAT) to V[(Me3SiNCH2CH2)3N], 1, forming OV[(Me3SiNCH2CH2)3N], 1-O, and the enthalpies of sulfur atom transfer (SAT) to 1 and V(N[t-Bu]Ar)3, 2 (Ar = 3,5-C6H3Me2), forming the corresponding sulfides SV[(Me3SiNCH2CH2)3N], 1-S, and SV(N[t-Bu]Ar)3, 2-S, have been measured by solution calorimetry in toluene solution using dbabhNO (dbabhNO = 7-nitroso-2,3:5,6-dibenzo-7-azabicyclo[2.2.1]hepta-2,5-diene) and Ph3SbS as chalcogen atom transfer reagents. The V-O BDE in 1-O is 6.3 ± 3.2 kcal·mol(-1) lower than the previously reported value for 2-O and the V-S BDE in 1-S is 3.3 ± 3.1 kcal·mol(-1) lower than that in 2-S. These differences are attributed primarily to a weakening of the V-Naxial bond present in complexes of 1 upon oxidation. The rate of reaction of 1 with dbabhNO has been studied by low temperature stopped-flow kinetics. Rate constants for OAT are over 20 times greater than those reported for 2. Adamantyl isonitrile (AdNC) binds rapidly and quantitatively to both 1 and 2 forming high spin adducts of V(III). The enthalpies of ligand addition to 1 and 2 in toluene solution are -19.9 ± 0.6 and -17.1 ± 0.7 kcal·mol(-1), respectively. The more exothermic ligand addition to 1 as compared to 2 is opposite to what was observed for OAT and SAT. This is attributed to less weakening of the V-Naxial bond in ligand binding as opposed to chalcogen atom transfer and is in keeping with structural data and computations. The structures of 1, 1-O, 1-S, 1-CNAd, and 2-CNAd have been determined by X-ray crystallography and are reported. PMID:25280113
Diagnosis of triangular fibrocartilage complex injury using arthrography and MRI
Energy Technology Data Exchange (ETDEWEB)
Kato, Kiyonobu; Soejima, Osamu; Naito, Masatoshi [Fukuoka Univ. (Japan). School of Medicine
2001-09-01
Twenty patients (twenty-one wrists) with chronic ulnar wrist pain who had undergone radiocarpal arthrography and MRI before arthroscopic examination were evaluated to determine the usefulness of these preoperative diagnostic procedures (arthrogrphy and MRI) for the detection of triangular fibrocartilage complex (TFCC) injury. Based on the arthroscopic findings, the sensitivity and specificity of arthrography were 63% and 100% respectively for detecting TFCC lesions, while they were 68% and 50% respectively for MRI. Although no significant superiority was observed between arthrography and MRI in this study, further improrumchts in the preoperative diagnostic procedures are still needed in order to more accurately detect TFCC injuries. (author)
Generation of Triangular Meshes for Complex Domains on the Plane
Directory of Open Access Journals (Sweden)
Barbara Glut
2001-01-01
Full Text Available Many physical phenomena can be modeled by partial differential equations. The development of numerical methods based on the spatial subdivision of a domain into finite elements immediately extended interests to the tasks of generating a mesh. With the availability of versatile field solvers and powerful computers, the simulations of ever incrcasing geometrical and physical complexity are attempted. At some point the main bottleneck becomes the mesh generation itself. The paper presents a detailed description of the triangular mesh generation scheme on the plane based upon the Delaunay triangulation. A mesh generator should be fully automatic and simplify input data as much as possible. It should offer rapid gradation from small to large sizes of elements. The generated mesh must be always valid and of good quality. All these requirements were taken into account during the selection and elaboration of utilized algorithms. Successive chapters describe procedures connected with the specification of a modeled domain, generation and triangulation of boundary vertices, introducing inner nodes, improving the quality of the created mesh, and renumbering of vertices.
International Nuclear Information System (INIS)
The complexes formed by H2CO, CH3CHO, and (CH3)2CO with 1, 2, and 3 molecules of CO2 are studied by ab initio calculations. Three different types of heterodimers are observed, most containing a tetrel bond to the C atom of CO2, and some supplemented by a CH⋅⋅O H-bond. One type of heterodimer is stabilized by an anti-parallel arrangement of the C=O bonds of the two molecules. The binding energies are enhanced by methyl substitution on the carbonyl, and vary between 2.4 and 3.5 kcal/mol. Natural bond orbital analysis identifies a prime source of interaction as charge transfer into the π*(CO) antibonding orbital. Heterotrimers and tetramers carry over many of the geometrical and bonding features of the binary complexes, but also introduce O⋅⋅O chalcogen bonds. These larger complexes exhibit only small amounts of cooperativity
On the Reduction of a Complex Matrix to Triangular or Diagonal by Consimilarity
Institute of Scientific and Technical Information of China (English)
Tongsong Jiang; Musheng Wei
2006-01-01
Two n × n complex matrices A and B are said to be consimilar if S-1 AS = B for some nonsingular n × n complex matrix S. This paper, by means of real representation of a complex matrix, studies problems of reducing a given n × n complex matrix A to triangular or diagonal form by consimilarity, not only gives necessary and sufficient conditions for contriangularization and condiagonalization of a complex matrix, but also derives an algebraic technique of reducing a matrix to triangular or diagonal form by consimilarity.
The allylic chalcogen effect in olefin metathesis
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Yuya A. Lin
2010-12-01
Full Text Available Olefin metathesis has emerged as a powerful tool in organic synthesis. The activating effect of an allylic hydroxy group in metathesis has been known for more than 10 years, and many organic chemists have taken advantage of this positive influence for efficient synthesis of natural products. Recently, the discovery of the rate enhancement by allyl sulfides in aqueous cross-metathesis has allowed the first examples of such a reaction on proteins. This led to a new benchmark in substrate complexity for cross-metathesis and expanded the potential of olefin metathesis for other applications in chemical biology. The enhanced reactivity of allyl sulfide, along with earlier reports of a similar effect by allylic hydroxy groups, suggests that allyl chalcogens generally play an important role in modulating the rate of olefin metathesis. In this review, we discuss the effect of allylic chalcogens in olefin metathesis and highlight its most recent applications in synthetic chemistry and protein modifications.
The allylic chalcogen effect in olefin metathesis
Lin, Yuya A
2010-01-01
Summary Olefin metathesis has emerged as a powerful tool in organic synthesis. The activating effect of an allylic hydroxy group in metathesis has been known for more than 10 years, and many organic chemists have taken advantage of this positive influence for efficient synthesis of natural products. Recently, the discovery of the rate enhancement by allyl sulfides in aqueous cross-metathesis has allowed the first examples of such a reaction on proteins. This led to a new benchmark in substrate complexity for cross-metathesis and expanded the potential of olefin metathesis for other applications in chemical biology. The enhanced reactivity of allyl sulfide, along with earlier reports of a similar effect by allylic hydroxy groups, suggests that allyl chalcogens generally play an important role in modulating the rate of olefin metathesis. In this review, we discuss the effect of allylic chalcogens in olefin metathesis and highlight its most recent applications in synthetic chemistry and protein modifications. PMID:21283554
Generation of Triangular Meshes for Complex Domains on the Plane
Barbara Glut; Tomasz Jurczyk
2001-01-01
Many physical phenomena can be modeled by partial differential equations. The development of numerical methods based on the spatial subdivision of a domain into finite elements immediately extended interests to the tasks of generating a mesh. With the availability of versatile field solvers and powerful computers, the simulations of ever incrcasing geometrical and physical complexity are attempted. At some point the main bottleneck becomes the mesh generation itself. The paper presents a deta...
Directory of Open Access Journals (Sweden)
Jairo A Díaz
Full Text Available The present study describes and documents self-assembly of geometric triangular chiral hexagon crystal like complex organizations (GTCHC in human pathological tissues. The authors have found this architectural geometric expression at macroscopic and microscopic levels mainly in cancer processes. This study is based essentially on macroscopic and histopathologic analyses of 3000 surgical specimens: 2600 inflammatory lesions and 400 malignant tumours. Geometric complexes identified photographically at macroscopic level were located in the gross surgical specimen, and these areas were carefully dissected. Samples were taken to carry out histologic analysis. Based on the hypothesis of a collision genesis mechanism and because it is difficult to carry out an appropriate methodological observation in biological systems, the authors designed a model base on other dynamic systems to obtain indirect information in which a strong white flash wave light discharge, generated by an electronic device, hits over the lines of electrical conductance structured in helicoidal pattern. In their experimental model, the authors were able to reproduce and to predict polarity, chirality, helicoid geometry, triangular and hexagonal clusters through electromagnetic sequential collisions. They determined that similar events among constituents of extracelular matrix which drive and produce piezoelectric activity are responsible for the genesis of GTCHC complexes in pathological tissues. This research suggests that molecular crystals represented by triangular chiral hexagons derived from a collision-attraction event against collagen type I fibrils emerge at microscopic and macroscopic scales presenting a lateral assembly of each side of hypertrophy helicoid fibers, that represent energy flow in cooperative hierarchically chiral electromagnetic interaction in pathological tissues and arises as a geometry of the equilibrium in perturbed biological systems. Further
Arthroscopic Trans-osseous Suture of Peripheral Triangular Fibrocartilage Complex Tear.
Jegal, Midum; Heo, Kang; Kim, Jong Pil
2016-10-01
The importance of foveal repair of the triangular fibrocartilage complex (TFCC) on stability of the distal radioulnar joint (DRUJ) has been emphasized with increasing knowledge of the anatomy and biomechanics of the TFCC and DRUJ. Although both open and arthroscopic techniques have been described for improving DRUJ stability, there has been a marked evolution of arthroscopic TFCC repair technique with successful clinical outcome. Recently, an arthroscopic trans-osseous technique has been described to repair foveal tears of the TFCC. The advantage of the technique is that it allows for anatomical repair of both the superficial and deep layers. This article describes the details of this novel technique. PMID:27595945
Anion Transport with Chalcogen Bonds.
Benz, Sebastian; Macchione, Mariano; Verolet, Quentin; Mareda, Jiri; Sakai, Naomi; Matile, Stefan
2016-07-27
In this report, we introduce synthetic anion transporters that operate with chalcogen bonds. Electron-deficient dithieno[3,2-b;2',3'-d]thiophenes (DTTs) are identified as ideal to bind anions in the focal point of the σ holes on the cofacial endocyclic sulfur atoms. Anion binding in solution and anion transport across lipid bilayers are found to increase with the depth of the σ holes of the DTT anionophores. These results introduce DTTs and related architectures as a privileged motif to engineer chalcogen bonds into functional systems, complementary in scope to classics such as 2,2'-bipyrroles or 2,2'-bipyridines that operate with hydrogen bonds and lone pairs, respectively. PMID:27433964
Fontès, D
2006-11-01
Lesions of the triangular fibrocartilage complex of the wrist (TFCC) have perfectly been dismembered by Andrew Palmer and have largely benefited from progress of arthroscopy of the wrist. One distinguishes thus traumatic lesions (class 1) individualized according to their localization, central (1-A), ulnar (1-B), radial (1-D) or distal (1-C). Central lesions are classically associated to a positive ulnar variance. The clinical symptomatology evokes a meniscal like syndrome of the wrist. In case of failure of the medical treatment, it will be necessary to propose a surgical procedure guided by histopathology of the triangular complex. Thus, ulnar peripheral richly vascularized lesions (1-B) could therefore potentially heal and will have to benefit by an attempt of surgical reattachment (arthroscopic technique of Whipple, Poehling or other techniques) or by an osteosynthesis in case of fracture on the basis on the ulnar styloid process. Central fibrocartilage lesions (1-A) or radial avulsions (1-D) are less vascularized and have therefore little probability to heal; they will benefit then ideally from the endoscopic debridement of unstable flaps of the central portion of TFCC. No immobilization is required and rehabilitation is immediately undertaken. Less frequent class 1-C lesions justify in our practice a simple arthroscopic regularization, alone complete ruptures could have necessitate a direct suture. Class 2 degenerative lesions are graduated (A to E) according to evolution of the chondromalacia of the ulnar head and carpal bone, perforation of the central disc and lunotriquetral ligament degeneration. They are usually associated with a constitutional or an acquired ulnar plus variance syndrome, for example after a distal radius fracture malunion. The clinical symptomatology needs to differentiate them from the simple frequent physiological perforations after the age of 50 years. Arthroscopy will allow to regularize unstable non-vascularized lesions and to
Energy Technology Data Exchange (ETDEWEB)
Nakamura, Toshiyasu [Fujita Health Univ., Nagoya (Japan). Second Hospital; Yabe, Yutaka; Horiuchi, Yukio; Kikuchi, Yoshito; Makita, Satoo
1996-08-01
Advances in magnetic resonance imaging (MRI) now allow for the visualization of small structures, such as the triangular fibrocartilage complex (TFCC) of the wrist. Recent investigators suggested that MRI is useful in delineation of the TFCC itself and its abnormality, and supported that diagnostic value of MRI for the TFCC tears is almost equal to those of arthrography and arthroscopy. In contrast, there were several reports that representation of the TFCC in MRI was less worth than in arthrography. Further, it was reported that MRI was not useful because abnormal findings existed at normal volunteers` wrists. Recent development of the pulse sequence is remarkable, such as gradient echo, fast spin echo and fat suppression method. However, as the previous MR studies of the TFCC mainly using conventional spin echo pulse sequence, there were a few comparison of each pulse sequence and we do not know how each pulse sequence delineates the TFCC. Therefore, we studied MRI of the TFCC using several pulse sequence in normal volunteers, and compared MR slices of the TFCC with corresponding histological sections to evaluate shape detectability of MRI. (J.P.N.)
Energy Technology Data Exchange (ETDEWEB)
Bae, Won C.; Chang, Eric Y.; Chung, Christine B. [VA San Diego Healthcare System, Radiology Service, San Diego, CA (United States); University of California-San Diego, Department of Radiology, San Diego, CA (United States); Ruangchaijatuporn, Thumanoon [Mahidol University, Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine Ramathibodi Hospital, Rachathewi, Bangkok (Thailand); Biswas, Reni; Du, Jiang; Statum, Sheronda [University of California-San Diego, Department of Radiology, San Diego, CA (United States)
2016-04-15
To evaluate pathology of the triangular fibrocartilage complex (TFCC) using high-resolution morphologic magnetic resonance (MR) imaging, and compare with quantitative MR and biomechanical properties. Five cadaveric wrists (22-70 years) were imaged at 3 T using morphologic (proton density weighted spin echo, PD FS, and 3D spoiled gradient echo, 3D SPGR) and quantitative MR sequences to determine T2 and T1rho properties. In eight geographic regions, morphology of TFC disc and laminae were evaluated for pathology and quantitative MR values. Samples were disarticulated and biomechanical indentation testing was performed on the distal surface of the TFC disc. On morphologic PD SE images, TFC disc pathology included degeneration and tears, while that of the laminae included degeneration, degeneration with superimposed tear, mucinous transformation, and globular calcification. Punctate calcifications were highly visible on 3D SPGR images and found only in pathologic regions. Disc pathology occurred more frequently in proximal regions of the disc than distal regions. Quantitative MR values were lowest in normal samples, and generally higher in pathologic regions. Biomechanical testing demonstrated an inverse relationship, with indentation modulus being high in normal regions with low MR values. The laminae studied were mostly pathologic, and additional normal samples are needed to discern quantitative changes. These results show technical feasibility of morphologic MR, quantitative MR, and biomechanical techniques to characterize pathology of the TFCC. Quantitative MRI may be a suitable surrogate marker of soft tissue mechanical properties, and a useful adjunct to conventional morphologic MR techniques. (orig.)
Theoretical Analysis of Pnicogen and Chalcogen Bonds in H2XP…SHY Complexes%H2XP…SHY复合物中磷键与硫键的理论研究
Institute of Scientific and Technical Information of China (English)
刘玉震; 黎安勇
2015-01-01
The MP2 and CCSD(T) ab initio quantum chemistry methods were applied to study the pnicogen bonds X―P…S and chalcogen bonds Y―S…P formed between PH2X and SHY (X, Y=H, F, Cl, Br) and the effects of the substituents X and Y on the bonds. Calculated results show that the chalcogen bonds are stronger than the pnicogen bonds. Strongly electronegative substituents that are connected to the Lewis acid strengthened the bonds and significantly affected the structures and properties of the monomers. Conversely, the substituents connected to the Lewis bases produced opposite effects. The energies of chalcogen bonds were 8.37-23.45 kJ∙mol-1;the strongest chalcogen bond was found in the structure HFS-PH3 using the CCSD (T) method with a bonding energy of 16.04 kJ∙mol-1. The energies of pnicogen bonds were in the range 7.54-14.65 kJ∙mol-1;the strongest pnicogen bond was found in H2FP-SH2 using CCSD(T) with a bonding energy 12.52 kJ∙mol-1. The most important factors for bond strength for both types of bonds were the exchange and electrostatic energies. The hyperconjugations lp(S)-σ*(PX) and lp(P)-σ*(SY) play important roles in the formation of the pnicogen and chalcogen bonds, which both lead to polarization of the monomers. Polarization caused by the chalcogen bond is larger than that by the pnicogen bond, resulting in the chalcogen bond having less of a covalent character.%用从头算量子化学方法MP2与CCSD(T)研究了H2XP和SHY (X, Y=H, F, Cl, Br)分子的P与S之间形成的磷键X―P…S与硫键Y―S…P的本质与规律以及取代基X与Y对成键的影响.计算结果表明,硫键比磷键强,连接在Lewis酸上的取代基的电负性增大导致形成的磷键或硫键增强,键能增大,对单体的结构和性质的影响也增大；而连接在Lewis碱上的取代基效应则相反.硫键键能为8.37-23.45 kJ∙mol-1,最强的硫键结构是Y电负性最大而X电负性最小的HFS…PH3, CCSD(T)计算的键能是16.04 kJ∙mol-1
Hess, Florian; Farshad, Mazda; Sutter, Reto; Nagy, Ladislav; Schweizer, Andreas
2012-11-01
We performed this study to investigate whether discrepancy of bilateral dorsovolar shift of the distal radioulnar joint (DRUJ) is decisive for the diagnosis of DRUJ instability. Although several cadaver studies have quantified the amount of physiological dorsovolar shift, so far, there is no reliable method of quantification of DRUJ mobility in daily practice. The aim was to describe a novel sonographic method of quantifying DRUJ instability and evaluate its reliability and validity. In this study, 40 healthy volunteers and 17 patients with complete rupture of the triangular fibrocartilage complex (TFCC) underwent sonographic quantification of the grade of instability of their DRUJ bilaterally. Dorsovolar ulnar head translation relative to the distal radius was quantified by means of ultrasonography performed in a transversal plane through the ulnar head and Lister tubercle. Measurements were done while actively pressing the volar surface of the hand onto a brick 30 degrees pronated, and after lifting the hand. A quotient Q of the radioulnar distance (distance between the dorsal radius surface and the ulnar head) between the unloaded and loaded wrist was calculated for differentiation of a normal and unstable DRUJ. The Q ratio of the 17 patients with unilateral TFCC lesion was significantly different between the pathologic side and the contralateral wrist (1.19 vs. 0.54, p 0.8 was found to be a reasonable cut-off for pathologic laxity of the DRUJ with a sensitivity of 88% and a specificity of 81%. A quotient Q > 0.8 determines instability of the DRUJ reliably. This was a level II diagnostic study. PMID:24179720
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Asem A. Al-Hiari
2013-05-01
Full Text Available Objectives: The aims of the study were to evaluate the role of magnetic resonance arthrography (MRA of the wrist in detecting full-thickness tears of the triangular fibrocartilage complex (TFCC and to compare the results of the magnetic resonance arthrography (MRA with the gold standard arthroscopic findings. Methods:The study was performed at King Hussein Medical Center, Amman, Jordan, between January 2008 and December 2011. A total of 42 patients (35 males and 7 females who had ulnar-sided wrist pain and clinical suspicions of TFCC tears were included in the study. All patients underwent wrist magnetic resonance arthrography (MRA and then a wrist arthroscopy. The results of MRA were compared with the arthroscopic findings. Results: After comparison with the arthroscopic findings, the MRA had three false-negative results (sensitivity = 93% and no false-positive results. A total of 39 patients were able to return to work. Satisfaction was high in 38 of the patients and 33 had satisfactorypain relief. The sensitivity of the wrist MRA in detecting TFCC full-thickness tears was 93% (39, and specificity was 80% (16/20. The overall accuracy of wrist arthroscopy in detecting a full-thickness tear of the TFCC in our study was 85% (29/34. Conclusion: These results illustrate the role of wrist MRA in assessing the TFCC pathology and suggest its use as the first imaging technique, following a plain X-ray, in evaluating patients with chronic ulnar side wrist pain with suspected TFCC injuries.
Simultaneous triangularization
Radjavi, Heydar
2000-01-01
A collection of matrices is said to be triangularizable if there is an invertible matrix S such that S1 AS is upper triangular for every A in the collection. This generalization of commutativity is the subject of many classical theorems due to Engel, Kolchin, Kaplansky, McCoy and others. The concept has been extended to collections of bounded linear operators on Banach spaces: such a collection is defined to be triangularizable if there is a maximal chain of subspaces of the Banach space, each of which is invariant under every member of the collection. Most of the classical results have been generalized to compact operators, and there are also recent theorems in the finite-dimensional case. This book is the first comprehensive treatment of triangularizability in both the finite and infinite-dimensional cases. It contains numerous very recent results and new proofs of many of the classical theorems. It provides a thorough background for research in both the linear-algebraic and operator-theoretic aspects of tr...
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Marcelo Sthel
2013-05-01
Full Text Available The concept of sustainable complex triangular cells may be applied to an individual of any human society. This concept was introduced in two recent articles. A case study was proposed to show the applicability of this new concept to Indian populations without contact with civilization and with a low environmental impact. Here we propose to apply this concept to a recent study, which claims that the concept of “common but differentiated responsibilities” refers to the emissions of individuals instead of nations. The income distribution of a country was used to estimate how its fossil fuel CO2 emissions are distributed among its citizens and, from that a global CO2 distribution was constructed. We propose the extension of the concept of complex triangular cells where its area would be equivalent to the CO2 emission per individual. In addition, a new three-dimensional geometric model for the regular hexagonal structure is offered in which the sharing of natural resources (human cooperation is employed to reduce CO2 emissions in two scenarios by 2030.
Guo, Xin; An, Xiulin; Li, Qingzhong
2015-04-01
Quantum-chemical calculations have been performed for the chalcogen- and halogen-bonded complexes of F2CSe with a series of nitrogen bases (N2, NCH, NH3, NHCH2, NCLi, and NMe3) and dihalogen molecules (BrCl, ClF, and BrF), respectively. Both types of interactions are mainly driven by the electrostatic and orbital interactions. The chalcogen bond becomes stronger in the order of NCH (sp) < NH3 (sp(3)) < NHCH2 (sp(2)), showing some inconsistence with the electronegativity of the hybridized N atom. The Li and methyl groups have an enhancing effect on the strength of chalcogen bond; however, the former is jointly achieved through the electrostatic and orbital interactions, whereas the orbital interaction has dominant contribution to the latter enhancement. The halogen bond with F2CX (X = O, S, Se) as the electron donor is stronger for the heavier chalcogen atom, exhibiting a reverse dependence on the chalcogen atom with that in hydrogen bonds. The halogen bond is further strengthened by the presence of chalcogen bond in the ternary complexes. In addition, CSD research confirms the abundance of Se···N interaction in crystal materials. PMID:25797149
Congenital Triangular Alopecia
Yin Li, Vincent Chum; Yesudian, Paul Devakar
2015-01-01
Congenital triangular alopecia (CTA) also known as temporal triangular alopecia is a benign noncicatricial pattern of hair loss. It typically affects the frontotemporal region and rarely involves the temporoparietal or occipital scalp. It is a nonprogressive disorder that presents as a triangular, oval or lancet-shaped patch of alopecia. CTA can manifest at birth or develop later in life. The exact etiology of this condition remains unknown. Rarely, it may be associated with other disorders s...
Understanding the effect of substitution on the formation of S. . .F chalcogen bond
Indian Academy of Sciences (India)
RAHUL SHUKLA; DEEPAK CHOPRA
2016-10-01
In this study, we have investigated the effect of substitution on the formation of S. . .F non-covalent interactions in XHS. . .FCH₃ complexes (X= −H, −F, −Cl, −OH, −OCH₃, −NH₂, −NHCH₃, −NO₂, −CN) at MP2/aug-cc-pVDZ level of theory. The formation of S. . .F chalcogen bonds was observed in all the cases, except for X = −H. The binding energy of the S. . .F non-covalent interactions is strongly dependent on the nature of the substituent groups. The energy decomposition analysis revealed that electrostatic and exchangeenergy component are the dominant contributors towards the stability of these interactions. The topological analysis established the presence of the S. . .F chalcogen bond due to the presence of a bond critical point exclusively between sulphur and fluorine atoms representing a closed-shell interaction. The natural bondorbital analysis shows that the stability of the interaction comes from a charge transfer from F(lp) to σ* (S-X) orbital transition.
Energy Technology Data Exchange (ETDEWEB)
Lee, Ryan K.L.; Ng, Alex W.H.; Tong, Cina S.L.; Griffith, James F. [The Chinese University of Hong Kong, Department of Imaging and Interventional Radiology, Prince Of Wales Hospital, Shatin (China); Tse, W.L.; Wong, C.; Ho, P.C. [The Chinese University of Hong Kong, Department of Imaging and Interventional Radiology, Prince Of Wales Hospital, Shatin (China); The Chinese University of Hong Kong, Department of Orthopedics, Prince Of Wales Hospital, Shatin (China)
2013-09-15
This study compares the diagnostic performance of multidetector CT arthrography (CTA), conventional 3-T MR and MR arthrography (MRA) in detecting intrinsic ligament and triangular fibrocartilage complex (TFCC) tears of the wrist. Ten cadaveric wrists of five male subjects with an average age 49.6 years (range 26-59 years) were evaluated using CTA, conventional 3-T MR and MRA. We assessed the presence of scapholunate ligament (SLL), lunotriquetral ligament (LTL), and TFCC tears using a combination of conventional arthrography and arthroscopy as a gold standard. All images were evaluated in consensus by two musculoskeletal radiologists with sensitivity, specificity, and accuracy being calculated. Sensitivities/specificity/accuracy of CTA, conventional MRI, and MRA were 100 %/100 %/100 %, 66 %/86 %/80 %, 100 %/86 %/90 % for the detection of SLL tear, 100 %/80 %/90 %, 60 %/80 %/70 %, 100 %/80 %/90 % for the detection of LTL tear, and 100 %/100 %/100 %, 100 %/86 %/90 %, 100 %/100 %/100 % for the detection of TFCC tear. Overall CTA had the highest sensitivity, specificity, and accuracy among the three investigations while MRA performed better than conventional MR. CTA also had the highest sensitivity, specificity, and accuracy for identifying which component of the SLL and LTL was torn. Membranous tears of both SLL and LTL were better visualized than dorsal or volar tears on all three imaging modalities. Both CT and MR arthrography have a very high degree of accuracy for diagnosing tears of the SLL, LTL, and TFCC with both being more accurate than conventional MR imaging. (orig.)
On the hardness of recognizing triangular line graphs
Anand, Pranav; Gera, Ralucca; Hartke, Stephen G; Stolee, Derrick
2010-01-01
Given a graph G, its triangular line graph is the graph T(G) with vertex set consisting of the edges of G and adjacencies between edges that are incident in G as well as being within a common triangle. Graphs with a representation as the triangular line graph of some graph G are triangular line graphs, which have been studied under many names including anti-Gallai graphs, 2-in-3 graphs, and link graphs. While closely related to line graphs, triangular line graphs have been difficult to understand and characterize. Van Bang Le asked if recognizing triangular line graphs has an efficient algorithm or is computationally complex. We answer this question by proving that the complexity of recognizing triangular line graphs is NP-complete via a reduction from 3-SAT.
Energy Technology Data Exchange (ETDEWEB)
Cerny, Milena; Marlois, Romain [Department of Diagnostic and Interventional Radiology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Rue du Bugnon 46, 1011 Lausanne (Switzerland); Theumann, Nicolas [Institute of Radiology, Clinique Hirslanden Bois-Cerf, Avenue d’Ouchy 31, 1006 Lausanne (Switzerland); Bollmann, Christof; Wehrli, Laurent [Department of Plastic and Hand Surgery, Clinique Longeraie and Centre Hospitalier Universitaire Vaudois, University of Lausanne, Avenue de la Gare 9, 1003 Lausanne (Switzerland); Richarme, Delphine [Institute of Radiology, Clinique Hirslanden Bois-Cerf, Avenue d’Ouchy 31, 1006 Lausanne (Switzerland); Meuli, Reto [Department of Diagnostic and Interventional Radiology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Rue du Bugnon 46, 1011 Lausanne (Switzerland); Becce, Fabio, E-mail: fabio.becce@chuv.ch [Department of Diagnostic and Interventional Radiology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Rue du Bugnon 46, 1011 Lausanne (Switzerland)
2013-10-01
Purpose: To determine the value of applying finger trap distraction during direct MR arthrography of the wrist to assess intrinsic ligament and triangular fibrocartilage complex (TFCC) tears. Materials and methods: Twenty consecutive patients were prospectively investigated by three-compartment wrist MR arthrography. Imaging was performed with 3-T scanners using a three-dimensional isotropic (0.4 mm) T1-weighted gradient-recalled echo sequence, with and without finger trap distraction (4 kg). In a blind and independent fashion, two musculoskeletal radiologists measured the width of the scapholunate (SL), lunotriquetral (LT) and ulna-TFC (UTFC) joint spaces. They evaluated the amount of contrast medium within these spaces using a four-point scale, and assessed SL, LT and TFCC tears, as well as the disruption of Gilula's carpal arcs. Results: With finger trap distraction, both readers found a significant increase in width of the SL space (mean Δ = +0.1 mm, p ≤ 0.040), and noticed more contrast medium therein (p ≤ 0.035). In contrast, the differences in width of the LT (mean Δ = +0.1 mm, p ≥ 0.057) and UTFC (mean Δ = 0 mm, p ≥ 0.728) spaces, as well as the amount of contrast material within these spaces were not statistically significant (p = 0.607 and ≥0.157, respectively). Both readers detected more SL (Δ = +1, p = 0.157) and LT (Δ = +2, p = 0.223) tears, although statistical significance was not reached, and Gilula's carpal arcs were more frequently disrupted during finger trap distraction (Δ = +5, p = 0.025). Conclusion: The application of finger trap distraction during direct wrist MR arthrography may enhance both detection and characterisation of SL and LT ligament tears by widening the SL space and increasing the amount of contrast within the SL and LT joint spaces.
The MRI diagnosis of triangular fibrocartilage complex injures in the wrist%腕三角纤维软骨复合体损伤的MRI诊断
Institute of Scientific and Technical Information of China (English)
万梦楠; 周胜法; 林锋; 陈久尊; 何家维; 郑显秋
2016-01-01
目的：探讨3．0T MRI在腕关节三角纤维软骨复合体（TFCC）损伤中的价值。方法回顾性分析26例TFCC损伤的MRI及X线平片、CT表现。结果26例X线检查13例阴性，5例茎突骨折，2例桡骨远端骨折，2例月骨坏死，6例尺骨径突阳性征。5例多层螺旋CT扫描，发现骨折或／和骨坏死2例。26例MRI检查中，21例诊断TFCC损伤，其中包括TFCC撕裂或穿孔8例，主要表现为在MRI脂肪抑制序列（ STIR）、2D MERGE及T2 WI上点状、条片状高信号，在T1 WI序列上呈等信号；9例腕部骨折（包括尺骨茎突5例，桡骨2例，腕骨2例）；3例三角骨或月骨坏死；8例尺桡骨或腕骨挫伤；10例腕关节腔积液。结论 TFCC形态细小而不规则，损伤时X线平片和CT检查价值有限，MRI多序列多方位薄层图像对显示其损伤及邻近骨质病变有重要价值。%Objective To investigate the value of 3.0 T MRI in triangular fibrocartilage complex (TFCC) injures in the wrist. Methods The MRI, X-ray and CT characteristics of 26 cases of TFCC injuries were analyzed retrospectively .Results Of the 26 cases with X-ray examination , 13 were negative cases , 5 ulnar styloid fracture , 2 distal radial fracture , 2 lunate necrosis and 6 positive ulnar styloid.5 cases underwent multi-slice CT scan, of which 2 cases had fracture or/and necrosis, others hadn’t ab-normal sign.Of the 26 patients underwent MRI examination , 21 cases were diagnosed as TFCC injuries including 8 cases with TF-CC tear or perforation which were mainly spotty and stripped hyperintense on MRI short time inverse recovery ( STIR ) , 2DMERGE and T2 WI and isointense on T 1 WI;9 were wrist fracture (5 ulnar styloid, 2 radius and 2 wrists);3 were triangular bone or lunate necrosis;8 were radius and ulna or wrist contusion and 10 wrist joints effusion.Bone contusion was long T 1 and long T2 , including bone fracture with bone trabecular or bone cortex breaking .Conclusion The
Kremer, Adrian; Fermi, Andrea; Biot, Nicolas; Wouters, Johan; Bonifazi, Davide
2016-04-11
The high-yielding synthesis of 2-substituted benzo-1,3-tellurazoles and benzo-1,3-selenazoles through a dehydrative cyclization reaction has been reported, giving access to a large variety of benzo-1,3-chalcogenazoles. Exceptionally, these aromatic heterocycles proved to be very stable and thus very handy to form controlled solid-state organizations in which wire-like polymeric structures are formed through secondary N⋅⋅⋅Y bonding interactions (SBIs) engaging the chalcogen (Y=Se or Te) and nitrogen atoms. In particular, it has been shown that the recognition properties of the chalcogen centre at the solid state could be programmed by selectively barring one of its σ-holes through a combination of electronic and steric effects exerted by the substituent at the 2-position. As predicted by the electrostatic potential surfaces calculated by quantum chemical modelling, the pyridyl groups revealed to be the stronger chalcogen bonding acceptors, and thus the best ligand candidate for programming the molecular organization at the solid state. In contrast, the thiophenyl group is an unsuitable substituent for establishing SBIs in this molecular system as it gives rise to chalcogen-chalcogen repulsion. The weaker chalcogen donor properties of the Se analogues trigger the formation of feeble N⋅⋅⋅Se contacts, which are manifested in similar solid-state polymers featuring longer nitrogen-chalcogen distances. PMID:26899235
Energy Technology Data Exchange (ETDEWEB)
Pfirrmann, C.W.A. [Dept. of Radiology, Veterans Administration Medical Center, San Diego, CA (United States); Dept. of Radiology, Orthopedic University Hospital Balgrist, Zurich (Switzerland); Theumann, N.H. [Dept. of Radiology, Veterans Administration Medical Center, San Diego, CA (United States); Service de Radiologie, CHUV, Lausanne (Switzerland); Chung, C.B.; Trudell, D.J.; Resnick, D. [Dept. of Radiology, Veterans Administration Medical Center, San Diego, CA (United States); Botte, M.J. [Div. of Orthopedic Surgery, Scripps Clinic and Research Foundation, La Jolla, CA (United States)
2001-12-01
Objective: To evaluate the dynamic morphologic changes of the triangular fibrocartilage complex (TFCC) during pronation and supination of the forearm using high-resolution MR arthrography in cadavers and to evaluate the impact of these changes on the diagnostic assessment of the normal and abnormal TFCC. Design and specimens: High-resolution MR arthrography of 10 wrists of cadaveric specimens was obtained in maximum pronation, in the neutral position, and in maximum supination of the forearm. The structures of the TFCC were evaluated by two musculoskeletal radiologists and correlated with anatomic sections. The position of the forearm that allowed the best visualization of normal structures and lesions of the TFCC was determined. Results: The shape and extent of the articular disc as well as the radial portions of the radioulnar ligaments did not change with pronation and supination. The articular disc was horizontal in the neutral position and tilted more distally to align with the proximal carpal row in pronation and supination. The fibers of the ulnar part of the radioulnar ligaments (ulnar attachment of the articular disc) revealed the most significant changes: their orientation was coronal in the neutral position and sagittal in positions of pronation and supination. The ulnomeniscal homologue was largest in the neutral position and was reduced in size during pronation and supination. The extensor carpi ulnaris tendon was centered in its groove in the neutral position and pronation. In supination this tendon revealed subluxation from this groove. The dorsal capsule of the distal radioulnar joint was taut in pronation, and the palmar capsule was taut in supination. The preferred forearm position for analysis of most of the structures of the TFCC was the neutral position, followed by the pronated position. The neutral position was rated best for the detection of ulnar and radial detachments of the TFCC, followed by the pronated position, except for two central
三角纤维软骨复合体的MRI 技术研究%Magnetic resonance imaging of the triangular fibrocartilage complex
Institute of Scientific and Technical Information of China (English)
纪涛涛; 毛传万; 王雪; 刘倩; 张瑞方; 叶信健; 严志汉; 何家维
2015-01-01
Objective To investigate the value of MR 3D fs SPGR(three-dimensional fat-suppressed spoiled gradient echo se-quence)in displaying the general structure of normal triangular fibrocartilage complex(triangular fibrocartilage disc,palm dorsal dis-tal radioulnar ligament,ulnolunate ligament,ulnotriquetral ligament,ulnar collateral ligament,extensor carpi sheath and articular disc homologues).Methods 1 5 normal adults(30 carpals)were examined withconventional sequences including axial fast spin-echo T1-weighted images (FSE T1 WI)or T2-weighted images (T2 WI),coronal fat-suppressed fast spin-echo T2-weighted images (FSE fsT2 WI)and coronal 3D fs SPGR.As well,3D image reconstruction was performed.Two experienced radiologists read the images with an agreement and recorded the display rate of general structure of TFCC.Results Triangular fibrocartilage disc,articular disc homologuespalm,dorsal distal radioulnar ligament,and extensor carpi sheath were totally showed on coronal and cross sections.Ulnolunate liga-ment and ulnotriquetral ligament were totally seen on the coronal plane,and the display rates on cross-section were 93.3%(28/30), 96.7%(29/30)respectively.Ulnar collateral ligament was seen on cross-section and coronal plane 83.3%(25/30),86.7%(26/30)re-spectively.Conclusion Coronal 3D fs SPGR sequence can be used as a regular sequence for observing TFCC and the surrounding lig-aments .%目的：探讨3.0T MRI 三维脂肪抑制扰相梯度回波技术(3D fs SPGR)对正常三角纤维软骨复合体(TFCC)的大体结构(三角纤维软骨盘、桡尺远端掌背侧韧带、尺月韧带、尺三角韧带、尺侧副韧带、尺侧腕伸肌腱鞘及关节盘同系物)的显示情况。方法成人健康志愿者15例(30例腕关节)，分别用轴位快速自旋回波 T1加权像(FSE T1 WI)或 T2加权像(T2 WI)，冠状位快速自旋回波脂肪抑制 T2加权像(FSE fsT2 WI)，冠状位3D fs SPGR 对30例腕关节进行常规扫描，后将3D 序列图像重建，由2
Congenital temporal triangular alopecia.
Bargman, H
1984-01-01
Congenital temporal triangular alopecia is a form of nonscarring alopecia that, as its name suggests, is present at birth. Four cases are reported. One patient underwent hair transplantation, which was successful and might be useful in other patients. Cases occurring in a father and his son suggest for the first time a genetic link.
Series of Reciprocal Triangular Numbers
Bruckman, Paul; Dence, Joseph B.; Dence, Thomas P.; Young, Justin
2013-01-01
Reciprocal triangular numbers have appeared in series since the very first infinite series were summed. Here we attack a number of subseries of the reciprocal triangular numbers by methodically expressing them as integrals.
TREATMENT OF TRIANGULAR FIBROCARTILAGE COMPLEX TEAR UNDER WRIST ARTHROSCOPY%腕关节镜下治疗三角纤维软骨复合体损伤
Institute of Scientific and Technical Information of China (English)
米琨; 刘武; 刘鹏飞; 俸志斌; 李玉文; 惠桂生
2011-01-01
目的 探讨腕关节镜下治疗三角纤维软骨复合体(triangular fibrocartilage complex,TFCC)损伤的方法及疗效.方法 2006年1月-2008年12月,收治TFCC损伤16例.男11例,女5例;年龄25～51岁,平均32.5岁.扭伤12例,跌伤4例.左侧10例,右侧6例.病程3个月～6年2个月.主要临床症状为腕关节尺侧疼痛、无力,用力握拳和提重物时疼痛明显.尺腕应力试验阳性14例,阴性2例.术前腕关节掌屈(45.58±5.18)°,背伸(41.22±3.83)°,桡偏(17.82±2.48)°,尺偏(21.35±4.61)°,旋前(69.85±8.36)°,旋后(70.13±6.34)°.术中根据腕关节镜下观察情况,对损伤按照Palmer刨伤性TFCC分类标准进行分类并行相应治疗.其中10例Ⅰ A类损伤行清理术;3例Ⅰ B类损伤中2例行缝合修补,1例缝合失败改部分切除术;2例Ⅰ C类损伤对损伤的三角软骨盘及尺月韧带和尺三角韧带进行清创;1例Ⅰ D类损伤采取汽化修整成形术.结果 术后切口均Ⅰ期愈合,未发生关节感染及神经、血管损伤等并发症.患者均获随访,随访时间14～38个月,平均18.5个月.15例恢复正常生活、工作,无腕关节尺侧疼痛发生;1例无疼痛发生,但腕关节无力.末次随访时腕关节掌屈(50.16±6.21)°,背伸(45.37±4.65)°,桡偏(18.95±3.56)°,尺偏(26.28±5.09)°,旋前(78.87±7.69)°,旋后(76.46±8.31)°,与术前相应指标比较差异均有统计学意义(JP＜0.05).采用Green-O'Brien功能评定方法进行评定,获优9例,良6例,可1例,优良率93.75%.结论 腕关节镜下治疗TFCC损伤既能明确诊断,又能进行相应处理,且创伤小,功能恢复快,可有效避免腕尺侧疼痛的发生.%Objective To evaluate the treatment and effects of wrist arthroscopy in tear of triangular fibrocartilage complex (TFCC). Methods Between January 2006 and December 2008, 16 patients with tear of TFCC were treated. Of 16 patients, 11 were male and 5 were female with an average age of 32.5 years (range, 25-51 years). Injury
Synthesized Optimization of Triangular Mesh
Institute of Scientific and Technical Information of China (English)
HU Wenqiang; YANG Wenyu
2006-01-01
Triangular mesh is often used to describe geometric object as computed model in digital manufacture, thus the mesh model with both uniform triangular shape and excellent geometric shape is expected. But in fact, the optimization of triangular shape often is contrary with that of geometric shape. In this paper, one synthesized optimizing algorithm is presented through subdividing triangles to achieve the trade-off solution between the geometric and triangular shape optimization of mesh model. The result mesh with uniform triangular shape and excellent topology are obtained.
Mironov, Yu. V.; Yarovoi, S. S.; Solodovnikov, S. F.; Fedorov, V. E.
2003-08-01
The first triangular thiofluoride cluster complex of molybdenum K5[Mo3S4F7(FHF)2]·2H2O with unexpected coordination of bifluoride ions has been synthesized by the reaction of Mo3S7Br4 with molten KHF2. The compound was characterized by single crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group Cmc21 with four formulas in unit cell of dimensions a=15.1060(20) Å,b=8.7820(9) Å,c=14.3358(13) Å,V=1901.8(4) Å3.
Institute of Scientific and Technical Information of China (English)
李开元; 何宇; 孙年怡; 郑伟虎; 刘沙鑫; 李浩
2015-01-01
This paper summarizes related rehabilitation development of triangular fibrocartilage complex(TFCC) injury, and discusses the problems of present rehabilitation treatment with rehabilitation concept of basing on patients, advocating strengthening occupational therapy and social psycho-logical intervention.%本文总结三角纤维软骨复合体（TFCC）损伤相关康复治疗发展，以患者为本的康复治疗理念探讨现今康复治疗手段的不足，主张加强作业治疗、社会心理干预。
Congenital Triangular Alopecia.
Yin Li, Vincent Chum; Yesudian, Paul Devakar
2015-01-01
Congenital triangular alopecia (CTA) also known as temporal triangular alopecia is a benign noncicatricial pattern of hair loss. It typically affects the frontotemporal region and rarely involves the temporoparietal or occipital scalp. It is a nonprogressive disorder that presents as a triangular, oval or lancet-shaped patch of alopecia. CTA can manifest at birth or develop later in life. The exact etiology of this condition remains unknown. Rarely, it may be associated with other disorders such as Down's syndrome and phakomatosis pigmentovascularis. The diagnosis is based on its distinct clinical appearance. Histologically, hair follicles are miniaturized and replaced by sparse vellus hair follicles. Tricoscopy using a polarized light handheld dermatoscope can be a useful diagnostic tool. CTA is often asymptomatic and remains unchanged throughout the life. No treatment is required. Surgical intervention with follicular unit hair transplantation can provide a satisfactory cosmetic result. In this paper, we have identified 126 cases of CTA in the published literature cited on PubMed between 1905 and 2015. From the available evidence, 79% of patients with CTA presented with unilateral hair loss, 18.5% with bilateral involvement and rarely, with occipital alopecia (2.5%). There was no gender predilection. These figures are entirely consistent with previously published data. Physicians should remember to consider CTA as a potential diagnosis in any patient presenting with a nonscarring alopecia in order to avoid unnecessary investigations and treatments. PMID:26180448
The dominant role of chalcogen bonding in the crystal packing of 2D/3D aromatics.
Fanfrlík, Jindřich; Přáda, Adam; Padělková, Zdeňka; Pecina, Adam; Macháček, Jan; Lepšík, Martin; Holub, Josef; Růžička, Aleš; Hnyk, Drahomír; Hobza, Pavel
2014-09-15
The chalcogen bond is a nonclassical σ-hole-based noncovalent interaction with emerging applications in medicinal chemistry and material science. It is found in organic compounds, including 2D aromatics, but has so far never been observed in 3D aromatic inorganic boron hydrides. Thiaboranes, harboring a sulfur heteroatom in the icosahedral cage, are candidates for the formation of chalcogen bonds. The phenyl-substituted thiaborane, synthesized and crystalized in this study, forms sulfur⋅⋅⋅π type chalcogen bonds. Quantum chemical analysis revealed that these interactions are considerably stronger than both in their organic counterparts and in the known halogen bond. The reason is the existence of a highly positive σ-hole on the positively charged sulfur atom. This discovery expands the possibilities of applying substituted boron clusters in crystal engineering and drug design.
International Nuclear Information System (INIS)
In a hydrodynamic model, with fluctuating initial conditions, the correlation between triangular flow and initial spatial triangularity is studied. The triangular flow, even in ideal fluid, is not strongly correlated with the initial triangularity. The correlation is largely reduced in viscous fluid. Elliptic flow on the other hand appears to be strongly correlated with initial eccentricity. Weak correlation between triangular flow and initial triangularity indicates that a part of triangular flow is unrelated to initial triangularity. Triangularity acquired during the fluid evolution also contributes to the triangular flow.
DEFF Research Database (Denmark)
Gushchin, Artem; Ooi, Bee Lean; Harris, Pernille;
2009-01-01
), was isolated and its structure determined using X-ray crystallography. W3SSe6Br4 upon reaction with H3PO2 gave a mixture of all of the [W3SxSe4-x(H2O)(9)](4+) species. After repeated chromatography, crystals of {[W-3(mu(3)-S)(mu(2)-Se)(3)(H2O)(7)Cl--(2)](2)CB[6]}Cl-4 center dot 12H(2)O (IV) were crystallized...
Walking Down the Chalcogenic Group of the Periodic Table: From Singlet to Triplet Organic Emitters.
Kremer, Adrian; Aurisicchio, Claudia; De Leo, Federica; Ventura, Barbara; Wouters, Johan; Armaroli, Nicola; Barbieri, Andrea; Bonifazi, Davide
2015-10-19
The synthesis, X-ray crystal structures, ground- and excited-state UV/Vis absorption spectra, and luminescence properties of chalcogen-doped organic emitters equipped on both extremities with benzoxa-, benzothia-, benzoselena- and benzotellurazole (1X and 2X ) moieties have been reported for the first time. The insertion of the four different chalcogen atoms within the same molecular skeleton enables the investigation of only the chalcogenic effect on the organisation and photophysical properties of the material. Detailed crystal-structure analyses provide evidence of similar packing for 2O -2Se , in which the benzoazoles are engaged in π-π stacking and, for the heavier atoms, in secondary X⋅⋅⋅X and X⋅⋅⋅N bonding interactions. Detailed computational analysis shows that the arrangement is essentially governed by the interplay of van der Waals and secondary bonding interactions. Progressive quenching of the fluorescence and concomitant onset of phosphorescence features with gradually shorter lifetimes are detected as the atomic weight of the chalcogen heteroatom increases, with the tellurium-doped derivatives exhibiting only emission from the lowest triplet excited state. Notably, the phosphorescence spectra of the selenium and tellurium derivatives can be recorded even at room temperature; this is a very rare finding for fully organic emitters. PMID:26471446
Parameterization for fitting triangular mesh
Institute of Scientific and Technical Information of China (English)
LIN Hongwei; WANG Guojin; LIU Ligang; BAO Hujun
2006-01-01
In recent years, with the development of 3D data acquisition equipments, the study on reverse engineering has become more and more important. However, the existing methods for parameterization can hardly ensure that the parametric domain is rectangular, and the parametric curve grid is regular. In order to overcome these limitations, we present a novel method for parameterization of triangular meshes in this paper. The basic idea is twofold: first, because the isotherms in the steady temperature do not intersect with each other, and are distributed uniformly, no singularity (fold-over) exists in the parameterization; second, a 3D harmonic equation is solved by the finite element method to obtain the steady temperature field on a 2D triangular mesh surface with four boundaries. Therefore, our proposed method avoids the embarrassment that it is impossible to solve the 2D quasi-harmonic equation on the 2D triangular mesh without the parametric values at mesh vertices. Furthermore, the isotherms on the temperature field are taken as a set of iso-parametric curves on the triangular mesh surface. The other set of iso-parametric curves can be obtained by connecting the points with the same chord-length on the isotherms sequentially. The obtained parametric curve grid is regular, and distributed uniformly, and can map the triangular mesh surface to the unit square domain with boundaries of mesh surface to boundaries of parametric domain, which ensures that the triangular mesh surface or point cloud can be fitted with the NURBS surface.
Use of ionic liquids in synthesis of nanocrystals, nanorods and nanowires of elemental chalcogens
Indian Academy of Sciences (India)
A Thirumurugan
2007-04-01
Nanocrystals of elemental chalcogens have been synthesized solvothermally by using elemental chalcogen powder (Se and Te) and NaBH4 in imidazolium[BMIM]-based ionic liquids as solvents at 180–200°C. Nanorods and nanowires of Se and Te have been obtained when polyethyleneglycol was used as a co-solvent. Se nanowires have been prepared by using an ionic liquid with a small amount of water at room temperature. Sulfur microspheres have been prepared by heating sulfur powder in a mixture of [BMIM][BF4] and polyethyleneglycol over the temperature range 150–250°C. The nanostructures obtained are single crystalline in all the cases.
Subjectivity, objectivity, and triangular space.
Britton, Ronald
2004-01-01
The author reviews his ideas on subjectivity, objectivity, and the third position in the psychoanalytic encounter, particularly in clinical work with borderline and narcissistic patients. Using the theories of Melanie Klein and Wilfred Bion as a basis, the author describes his concept of triangular space. A case presentation of a particular type of narcissistic patient illustrates the principles discussed.
Ultrasound fields from triangular apertures
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt
1996-01-01
The pulsed field from a triangular aperture mounted in an infinite, rigidbaffle is calculated. The approach of spatial impulse responses,as developed by Tupholme and Stepanishen, is used. By this both the emitted and received pulsed ultrasound field can be found for any transducerexcitation...
On triangular algebras with noncommutative diagonals
Institute of Scientific and Technical Information of China (English)
2008-01-01
We construct a triangular algebra whose diagonals form a noncommutative algebra and its lattice of invariant projections contains only two nontrivial projections. Moreover we prove that our triangular algebra is maximal.
Householder triangularization of a quasimatrix
Trefethen, Lloyd N.
2008-01-01
A standard algorithm for computing the QR factorization of a matrix A is Householder triangularization. Here this idea is generalized to the situation in which A is a quasimatrix, that is, a “matrix” whose “columns” are functions defined on an interval [a,b]. Applications are mentioned to quasimatrix leastsquares fitting, singular value decomposition, and determination of ranks, norms, and condition numbers, and numerical illustrations are presented using the chebfun system.
Institute of Scientific and Technical Information of China (English)
刘玉珂; 张敏; 张斌青; 郭会利; 陈伟; 杨静; 张国庆
2014-01-01
Objective To discuss the application value of weight-bearing MRI in the Diagnosis of injury of triangular fibrocartilage complex(TFCC) in the wrist. Mathods 22 cases with suspected injury of the triangular fibrocartilage complex were performed with conventional MR and weight-bearing MRI. 20 cases of them underwent arthroscopy. The findings of conventional MRI, weight-bearing MRI and arthroscopy were compared and analyzed. Results In 22 cases of injury of TFCC, 17 cases showed part tearing, including ulnar tearing in 12 cases, radius tear in 5 cases. Isointensity signal and High signal intensity of injury of TFCC were revealed on T1WI and T2WI respectively, and the injury range was no more than half of the TFCC. In weight-bearing MRI GE-STIR sequence, the signal is more higher and more limited than conventional MRI, and the boundary was more clear. The signal was more higher and the surrounding soft tissue edema showed more obvious. 5 cases showed complete tearing, and the shape was irregular and the signal was heterogeneously increased in conventional MRI. The shape was more irregular and the signal was higher in weight-bearing MRI, and the surrounding soft tissue edema was more obvious. 9 cases were associated with cystic fluid in the radius-ulnar joint. 8 cases were associated with dislocation of radius-ulnar joint, and 7 cases associated with ulnar-sided wrist impingement syndromes, and 4 cases associated with bone marrow edema of radius or ulnar. Conclusion Compared with conventional MRI, weight-bearing MRI could adequately reveal the injury of triangular fibrocartilage complex, and the combination of the two methods can improve the diagnostic accuracy of injury of TFCC.%目的：探讨负重位MRI在腕关节三角纤维软骨复合体（TFCC）损伤中的应用价值。方法搜集临床怀疑腕关节TFCC损伤的患者22例，均进行腕关节常规体位和负重位MRI扫描，其中20例行腕关节镜检查，对比分析TFCC常规体位与负重位
Institute of Scientific and Technical Information of China (English)
陈爽; 徐文东; 冯晓源
2008-01-01
Objective To compare direct magnetic resonance(MR)arthrography with arthroscopy of the wrist for evaluation of injury in the triangular fibrocartilage complex(TFCC).Methods Fourteen cases with suspicion of injury of triangular fibrocartilage complex were performed with conventional MR and direct MR arthrography,10 cases were done by arthroscopy.In the direct MR arthrography,needle placement was obtained using clinical landmark under sterile technique and fluoroscopy,intra-articular injection was performed at the radius-scaphoid space with 5-7 ml 0.3%mixture of Gadolinium (0.1 mmol/L)and saline(0.3 ml Gd-DTPA+100 ml saline).The findings of MRI and MR arthrography were analyzed with results of arthroscopy.Resuits (1)Among 14 cases with injury of TFCC,there were ulnar tear in 5cases,radius tear in 4 cases,complete tear in 5 cases(included 2 cases with long term rheumatoid).(2)High signal intensity and isointensity signal of injury of TFCC were revealed on STIR or T2 WI and T1 WIrespectively,normal hypointensity signal of the TFCC was partially or completely absent.Contrast media at the ulnar insertion(5 cases with ulnar tear)or radius attachment of the TFCC(4 cases with radius tear)were seen in the MR arthrography with difierent extent,5 cases with complete tear showed contrast media at the both ulnar insertion and radius attachment of the TFCC.The findings of MR arthrography were well corresponded with results of arthroscopy on the lesion site,including ulnar tear in 3 cases,radius tear in 4cases and complete tear in 3 cases.(3)Among 14 cases with TFCC,8 cases had dislocation of radius-ulnar joint,6 cases had bone contusion of radius or ulnar,synovial reaction was also clearly depicted on conventional MRI and direct MR arthrography in all cases.Conclusion Compared with results of arthroscopy,direct MR arthrography can adequately reveal the injury of the triangular fibrocartilage complex,synovial reaction and edema changes are depicted on conventional MRI.%目的 通
Institute of Scientific and Technical Information of China (English)
钟敏之; 曾旭文; 梁治平
2010-01-01
Objective To explore the clinical application of MRI technology in the injury of triangular fibrocartilage complex and its ligament. Clear its value in clinical treatment.Methods Review 5 normal volunteer and 21 cases patien whom pain in wrist. Evaluate the sequence of GRE T2、SE T1、STIR and 3D dynamic scan in the wrist. Results MRI play the important role to evaluate the TFCC、scapholunate ligament (SLL), and lunotriquetral ligament(LTL).In 21 cases pain of wrist patien, there were 8 cases suffer TFCC tears. SLL injure in 4 cases and TLT injure in 2 cases. The fracture in the wrist bone are 5 case. Rheumatoid arthritis are 4 case, Ischemia necrosis 2case. Conclusion The wrist injure often with TFCC and ligament lesion, it worth pay attention to clinic. The structure of wrist is complex, for accurate dialogic,we must use multi sequence and many orientation to show the anatomic.%目的 探讨MRI技术在腕三角纤维软骨体其周围韧带损伤的临床应用,明确其临床治疗价值.方法 对5名正常腕关节志愿者及21名腕关节痛患者进行观察,使用GRE T2、SE T1及STIR检查序列及动态腕关节扫描对腕三角纤维软骨复合体形态进行评价.结果 MRI在评价三角纤维软骨、月三角韧带、舟月间韧带起重要作用.21例腕关节痛患者三角纤维软骨撕裂8例,腕部骨折7例,类风湿性关节炎4例.腕骨缺血性坏死2例.结论 腕关节慢性损伤常伴有TFCC损伤,值得临床重视.腕关节结构复杂,在检查过程中必须多序列,多方位结合以协助诊断.
Defect chemistry and chalcogen diffusion in thin-film Cu{sub 2}ZnSnSe{sub 4} materials
Energy Technology Data Exchange (ETDEWEB)
Harvey, Steven P.; Repins, Ingrid; Teeter, Glenn [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, Colorado 80401 (United States)
2015-02-21
Selenium diffusion in polycrystalline thin-film Cu{sub 2}ZnSn(S,Se){sub 4} (CZTSe) on molybdenum-coated soda-lime glass substrates was investigated by in situ monitoring of the molybdenum back-contact resistance during high-temperature selenization treatments. In these measurements, selenium diffusion through the CZTSe layer results in conversion of the molybdenum layer to MoSe{sub 2}, increasing the sheet resistance of the film stack. By monitoring the rate of MoSe{sub 2} formation as a function of annealing temperature, an activation energy of 0.5 ± 0.1 eV has been measured for selenium diffusion in CZTSe. The partial pressure dependence of chalcogen diffusion suggests that chalcogen vacancies are not the defect controlling chalcogen diffusion in thin-film CZTSe.
Zero Field Splitting of the chalcogen diatomics using relativistic correlated wave-function methods
DEFF Research Database (Denmark)
Rota, Jean-Baptiste; Knecht, Stefan; Fleig, Timo;
2011-01-01
The spectrum arising from the (π*)2 configuration of the chalcogen dimers, namely the X21, a2 and b0+ states, is calculated using Wave-Function Theory (WFT) based methods. Two-component (2c) and four-component (4c) MultiReference Configuration Interaction (MRCI) and Fock-Space Coupled Cluster (FS...... by a two-parameter model; Δε, the π* spinor splitting by spin-orbit coupling (SOC) and K, the exchange integral between the π*1 and the π*-1 spinors with respectively angular momenta 1 and −1. This model holds for all systems under study with the exception of Po2....
Synthesis and crystal structure determination of Br2SeIBr polyhalogen–chalcogen
Indian Academy of Sciences (India)
A A Alemi; E Solaimani
2004-06-01
In this paper polyhalogen–chalcogen Br2SeIBr was synthesized and the crystal structure was determined by single crystal X-ray diffraction method. This compound was prepared in the temperature range 150–50°C which was brownish-red in colour and crystallized in monoclinic crystal system and space group 21/c with four molecules per unit cell. Lattice parameters were: = 6.3711(1), = 6.7522(2), = 16.8850(5) Å, = = 90°, = 95·96°, = 722·45 Å3.
UWB Directive Triangular Patch Antenna
Directory of Open Access Journals (Sweden)
A. C. Lepage
2008-01-01
Full Text Available Compact directive UWB antennas are presented in this paper. We propose an optimization of the F-probe fed triangular patch antenna. The new design achieves an impedance bandwidth of 69% (3–6.15 GHz and presents good radiation characteristics over the whole impedance bandwidth. The average gain is 6.1 dB. A time-domain study has been performed to characterize the antenna behavior in case a UWB pulse is used. Finally, we propose an alternative solution to facilitate the manufacturing process using metallized foam technology. It also improves the robustness of the antenna as well as reducing its cost.
Spectral properties of random triangular matrices
Basu, Riddhipratim; Ganguly, Shirshendu; Hazra, Rajat Subhra
2011-01-01
We provide a relatively elementary proof of the existence of the limiting spectral distribution (LSD) of symmetric triangular patterned matrices and also show their joint convergence. We also derive the expressions for the moments of the LSD of the symmetric triangular Wigner matrix using properties of Catalan words.
Constructing parametric triangular patches with boundary conditions
Institute of Scientific and Technical Information of China (English)
Hui Liu; Jun Ma; Fuhua Cheng
2008-01-01
The problem of constructing a parametric triangular patch to smoothly connect three surface patches is studied. Usually, these surface patches are defined on different parameter spaces. Therefore, it is necessary to define interpolation conditions, with values from the given surface patches, on the boundary of the triangular patch that can ensure smooth transition between different parameter spaces. In this paper we present a new method to define boundary conditions. Boundary conditions defined by the new method have the same parameter space if the three given surface patches can be converted into the same form through affine transformation. Consequently, any of the classic methods for constructing functional triangular patches can be used directly to construct a parametric triangular patch to connect given surface patches with G continuity. The resulting parametric triangular patch preserves precision of the applied classic method.
Antiplane response of isosceles triangular hill to incident SH waves
Institute of Scientific and Technical Information of China (English)
Qiu Faqiang; Liu Diankui
2005-01-01
In this paper, antiplane response of an isosceles triangular hill to incident SH waves is studied based on the method of complex function and by using moving coordinate system. The standing wave function, which can satisfy the governing equation and boundary condition, is provided. Furthermore, numerical examples are presented; the influences of wave number and angle of the incident waves and the angle of the hill's peak on ground motion are discussed.
Institute of Scientific and Technical Information of China (English)
谢仁国; 汤锦波; 唐天驷; 刘国峰; 王古衡; 张昌军; 刑树国
2011-01-01
Objective Ulnar side wrist pain is one of the commonest symptoms, mostly arised from the triangular fibrocartilage complex ( TFCC) injuries. Arthroscopy is considered as the golden standard for diagnosis of the wrist disorders, superior to the CT and MRI. The aim of this study is to observe the anatomic components of TFCC of the wrist morphologically and arthroscopically, and to obtain the accurate arthroscopic view by comparison. Methods Five fresh cadaver upper limbs were applied to observe distal aspect of TFCC by the routine radiocarpal approach and proximal aspect of TFCC hy a direct approach over the distal radioulnar joint. After arthroscopy and capsulotomy, The TFCC was exposed to examine its components visually, and to examine the corresponding sites under the arthroscope. TFCC was then detached from the distal ends of the radius and the ulna to measure its length and thickness. Results TFC was like a triangular disc , of which peripheral parts became thickened into the palmar radioulnar ligament ( PRU) and the dorsal radioulnar ligament ( DRU) . TFCC originated from the ulnar edge of distal radius. Its distal part inserted and surrounded the base of ulnar styloid process, and its proximal part inserted into the fovea of distal ulna. Compared with the morphological observations, the distal aspect of the TFCC originations was very smooth under the wrist arthroscope. There was no obvious distinction among TFC, PRU and DRU. The proximal aspect of TFCC seemed like an arc over the distal radius and the fovea. The round articular surface of the ulnar head and the sigmoid notch at ulnar side of the distal radius could be seen clearly. Conclusions Wrist arthrosopy is reliable to clarify the TFCC accurately, based on the anatomical and morphological guidance. The direct portal route over the distal radio-ulnar joint is availahle to observe the profound parts of PRU and DRU ligaments.%目的 观察腕尺侧三角纤维软骨复合体的大体结构和腕关节镜
Institute of Scientific and Technical Information of China (English)
徐静; 汤锦波; 贾中正; 谢仁国
2009-01-01
目的 研究在体前臂旋前、旋后不同运动范围内三角纤维软骨复合体(TFCC)深部和浅部纤维的运动学.方法 以螺旋CT扫描6名志愿者腕关节,分别获得前臂在旋前90°至旋后90°内每隔30°的运动范围内桡骨和尺骨远端图像,三维重建骨结构图像后经软件处理得到在腕关节旋前和旋后过程中,三角纤维软骨复合体深部、浅部纤维的长度变化.结果 前臂旋转运动中,旋前运动时TFCC背侧浅部纤维、掌侧深部纤维处于紧张状态,TFCC掌侧浅部纤维、背侧深部纤维处于放松状态.旋后运动时TFCC背侧浅部纤维、掌侧深部纤维处于放松状态,TFCC掌侧浅部纤维、背侧深部纤维则处于紧张状态.结论 前臂旋转运动过程中,掌背侧总同时有TFCC掌、背侧深部或浅部纤维处于紧张状态,维持了下尺桡关节的稳定性.%objective To investigate three-dimensional kinematics of the superficial and deep portion of triangular fibrocartilage complex (TFCC) in different parts of the forearm rotation.Methods Six wrists of 6 volunteers were used to obtain CT scans at different positions of the wrist.The wrists were scanned from 90°of pronation to 90°of supination at an interval of 30 degrees.The 3-dimensional radius and ulna were reconstructed with customized software and changes in length of the superficial and deep portion of TFCC during forearm rotation.Results In forearm pronation,the superficial dorsal portion and the deep palmar portion of the TFCC were tight.While the sperficial palmar portion and the deep dorsal potion of the TFCC were lax.In supination,the changes inlength of all these fibers were reverse.Conclusions In forearm rotation one portion fibers of dorsal TFCC and one portion fibers of palmar TFCC are tight,and this mechanism controls stability during DRUJ rotation.
Modulating the Electronic and Optical Properties of Tetragonal ZnSe Monolayers by Chalcogen Dopants.
Zhou, Jia; Li, Yang; Wu, Xiaohong; Qin, Wei
2016-07-01
The recently proposed three-atom-thick single-layer ZnSe sheet demonstrates a strong quantum confinement effect by exhibiting a large enhancement of band gap relative to the zinc blende (ZB) bulk phase. In this work, we aim at investigating the electronic and optical properties of this ultrathin tetragonal ZnSe single-layer sheet with various chalcogen dopant atoms, based on density functional theory (DFT). We find that these single-layer sheets with dopant atoms are still direct-band semiconductors with tunable band gaps, which can lead to strong light absorption and potential applications in solar energy harvesting. Theoretical optical absorbance results show that the S-doped ZnSe monolayer exhibits a higher absorption performance compared to other doped and undoped ZnSe monolayers. These findings pave a way for the modulation of novel ultrathin tetragonal ZnSe monolayers for a wealth of potential optoelectronic applications. PMID:26972924
Modification of palladium-based catalysts by chalcogenes for direct methanol fuel cells
Energy Technology Data Exchange (ETDEWEB)
Serov, Alexey Alexandrovich; Cho, Sung-Yong; Han, Sangil; Min, Myoungki; Chai, Geunseok; Nam, Kie Hyun; Kwak, Chan [Corporate R and D Center, Samsung SDI, Shin-dong 575, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-731 (Korea)
2007-08-15
Palladium-based catalysts, such as PdS{sub x}/C and PdSe{sub x}/C, have been developed as oxygen reduction catalysts for direct methanol fuel cells. Pd/C catalysts containing chalcogens have been synthesized and tested for oxygen reduction and the results have been analyzed based on changes in the palladium phase. Selenium addition to the catalyst promotes the oxygen reduction due to the modification of the palladium surface. However, sulfur reduces the oxygen reduction activity to a great extent as a result of semi-amorphous palladium phase formation. Both PdS{sub x}/C and PdSe{sub x}/C are highly methanol tolerant. (author)
Guo, Y.; Liu, D.; Robertson, J.
2015-04-01
It is predicted that Schottky barriers of the transition metal dichalcogenides MoSe2, MoTe2, WS2, WSe2, and WTe2 will suffer less from Fermi level pinning by chalcogen vacancies than does MoS2, because their vacancy formation energies are larger. The reduction in vacancy numbers will allow a greater degree of Schottky barrier height tuning by varying metal work function of the contacts in these compounds. The vacancy levels of WS2, WSe2 and MoSe2, and MoTe2 are also calculated to lie nearer midgap, so that ambipolar conduction will be easier in these compounds than in MoS2.
Triangular buckling patterns of twisted inextensible strips
Korte, A P; van der Heijden, G H M
2010-01-01
When twisting a strip of paper or acetate under high longitudinal tension, one observes, at some critical load, a buckling of the strip into a regular triangular pattern. Very similar triangular facets have recently been observed in solutions to a new set of geometrically-exact equations describing the equilibrium shape of thin inextensible elastic strips. Here we formulate a modified boundary-value problem for these equations and construct post-buckling solutions in good agreement with the observed pattern in twisted strips. We also study the force-extension and moment-twist behaviour of these strips by varying the mode number n of triangular facets.
Molecular rectification in triangularly shaped graphene nanoribbons.
Liu, Hongmei; Wang, Hongbo; Zhao, Jianwei; Kiguchi, Manabu
2013-02-15
We present a theoretical study of electron transport in tailored zigzag graphene nanoribbons (ZGNRs) with triangular structure using density functional theory together with the nonequilibrium Green's function formalism. We find significant rectification with a favorite electron transfer direction from the vertex to the right edge. The triangular ZGNR connecting to the electrode with one thiol group at each terminal shows an average rectification ratio of 8.4 over the bias range from -1.0 to 1.0 V. This asymmetric electron transport property originates from nearly zero band gap of triangular ZGNR under negative bias, whereas a band gap opens under positive bias. When the molecule is connected to the electrode by multithiol groups, the current is enhanced due to strong interfacial coupling; however, the rectification ratio decreases. The simulation results indicate that the unique electronic states of triangular ZGNR are responsible for rectification, rather than the asymmetric anchoring groups.
Functional Contractive Maps in Triangular Symmetric Spaces
Directory of Open Access Journals (Sweden)
Mihai Turinici
2013-01-01
Full Text Available Some fixed point results are given for a class of functional contractions acting on (reflexive triangular symmetric spaces. Technical connections with the corresponding theories over (standard metric and partial metric spaces are also being established.
Valldor, Martin; Rößler, Ulrich K; Prots, Yurii; Kuo, Chang-Yang; Chiang, Jen-Che; Hu, Zhiwei; Pi, Tun-Wen; Kniep, Rüdiger; Tjeng, Liu Hao
2015-07-20
Barium thio-oxocobaltate(II), Ba[CoS2/2 O2/2 ], was synthesized by the reaction of equimolar amounts of BaO, Co, and S in closed silica ampoules. The title compound (Cmcm, a=3.98808(3), b=12.75518(9), c=6.10697(4) Å) is isostructural to Ba[ZnSO]. The use of soft X-ray absorption spectroscopy confirmed that cobalt is in the oxidation state +2 and tetrahedrally coordinated. Its coordination consists of two sulfur and two oxygen atoms in an ordered fashion. High-temperature magnetic susceptibility data indicate strong low-dimensional spin-spin interactions, which are suggested to be closely related to the layer-type crystal structure and perhaps the ordered distribution of sulfur and oxygen. Antiferromagnetic ordering below TN =222 K is observed as an anomaly in the specific heat, coinciding with a significant lowering of the magnetic susceptibility. Density functional theory calculations within a generalized-gradient approximation (GGA)+U approach identify an antiferromagnetic ground state within the square-like two-dimensional layers of Co, and antiferromagnetic correlations for nearest and next nearest neighbors along bonds mediated by oxygen or sulfur. However, this magnetic state is subject to frustration by relatively strong interlayer couplings.
Classification and MR imaging of triangular fibrocartilage complex lesions%三角纤维软骨复合体损伤的分型及磁共振表现
Institute of Scientific and Technical Information of China (English)
詹惠荔; 刘悦; 白荣杰; 钱占华; 叶薇; 李亚雄; 吴伯栋
2016-01-01
Objective To explore the MRI characteristics of injuries of triangular fibrocartilage complex (TFCC),and provide imaging basis for the early diagnosis and treatment of the injuries.Methods A total of 10 healthy volunteers without wrist injuries and 200 patients from Beijing Jishuitan Hospital who complained ulnar-sided wrist pain and were highly suspected as the injury of TFCC underwent the wrist magnetic resonance examination.All subjects were in a prone position and underwent examination on coronal T1 WI scan and PD-FS on 3 planes respectively.Then the MRI characteristics of 3 healthy volunteers and 67 patients with TFCC injuries that confirmed by operation were analyzed.According to the comparative analysis of normal anatomy and Palmer classification,the injuries were classified and MRI features of different types of injuries were analyzed.At last,imaging findings were compared with surgical results.Results Three healthy volunteers without injuries showed mainly in low signal intensity on T1WI and PD-FS images.According to Palmer classification,there were 52 traumatic injuries (Ⅰ A 9,Ⅰ B 25,Ⅰ C 3,Ⅰ D 13,In addition,1 has central perforation and ulnar avulsion and 1 has ulnar and radial injuries simultaneously) and 15 degenerative injuries (Ⅱ A 5,Ⅱ B 1,ⅡC 2,Ⅱ D 1,Ⅱ E 6) among 67 patients.The central perforation mainly demonstrated as linear high signal perpendicular to the disk,and run in a sagittal line.The ulnar,distal,and radial avulsion mainly showed the injuries were irregular,the structures were ambiguous,and there was high signal intensity in the injured structures on PD-FS.Degenerative injuries demonstrated the irregularity of TFC and heterogeneous signals on PD-FS.There were mixed intermediate-high signals and changes in the articular cartilage of lunate and ulna,high signal in the lunotriquetral ligament and ulnocarpal or radioulnar arthritis.Conclusion MRI can demonstrate the anatomy of TFCC accurately,evaluate and make the general
Kadlag, Yogita; Becker, Harry
2016-06-01
187Re-187Os systematics, abundances of highly siderophile elements (HSE: Re, PGE, and Au), chalcogen elements (Te, Se, and S), and some major and minor elements were determined in physically separated components of the Allende (CV3) and Murchison (CM2) carbonaceous chondrites. Substantial differences exist in the absolute and relative abundances of elements in the components, but the similarity of calculated and literature bulk rock abundances of HSE and chalcogens indicate that chemical complementarity exists among the components, with CI chondrite-like ratios for many elements. Despite subsequent alteration and oxidation, the overall cosmochemical behavior of most moderately to highly siderophile elements during high-temperature processing has been preserved in components of Allende at the sampling scale of the present study. The 187Re-187Os systematics and element variations of Allende are less disturbed compared with Murchison, which reflects different degrees of oxidation and alteration of these meteorites. The HSE systematics (with the exception of Au) is controlled by two types of materials: Pd-depleted condensates and CI chondrite-like material. Enrichment and heterogeneous distribution of Au among the components is likely the result of hydrothermal alteration. Chalcogen elements are depleted compared with HSE in all components, presumably due to their higher volatility. Small systematic variations of S, Se, and Te in components bear the signature of fractional condensation/partial evaporation and metal-sulfide-silicate partitioning.
Energy Technology Data Exchange (ETDEWEB)
Meenatchi, Boominathan [Cauvery College for Women, Tamilnadu (India); Renuga, Velayutham [National College, Tamilnadu (India); Manikandan, Ayyar [Bharath Institute of Higher Education and Research, Bharath University, Tamilnadu (India)
2016-03-15
Green synthesis of selenium (chalcogen) nanoparticles (SeNPs) has been successfully attained by simple wet chemical method that involves the reaction of six different protic ionic liquids with imidazolium cations and sodium hydrogen selenide (NaHSe) in the presence of poly ethylene glycol-600 (PEG-600) as an additional stabilizer. The obtained SeNPs were characterized using UV spectral (UV), Fourier transform infra-red (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscope (SEM) with energy dispersive X-ray (EDX) and high resolution transmission electron microscope (TEM) analysis. The results illustrate that the synthesized SeNPs are spherical in shape with size ranging 19-24 nm and possess good optical property with greater band gap energy, high thermal stability up to 330 .deg. C, low melting point of 218-220 .deg. C comparing to precursor selenium. Using the synthesized SeNPs, two chalcogenides such as ZnSe and CdSe semiconductor nanoparticles were synthesized and characterized using XRD, SEM with EDX and TEM analysis. The fabricated CdSe and ZnSe nanoparticles appeared like pebble and cluster structure with particle size of 29.97 nm and 22.73 nm respectively.
Sharma, Subash; Kalita, Golap; Vishwakarma, Riteshkumar; Zulkifli, Zurita; Tanemura, Masaki
2015-01-01
In-plane heterostructure of monolayer hexagonal boron nitride (h-BN) and graphene is of great interest for its tunable bandgap and other unique properties. Here, we reveal a H2-induced etching process to introduce triangular hole in triangular-shaped chemical vapor deposited individual h-BN crystal. In this study, we synthesized regular triangular-shaped h-BN crystals with the sizes around 2-10 μm on Cu foil by chemical vapor deposition (CVD). The etching behavior of individual h-BN crystal w...
Optimizing triangular mesh generation from range images
Lu, Tianyu; Yun, David Y.
2000-03-01
An algorithm for the automatic reconstruction of triangular mesh surface model form range images is presented. The optimal piecewise linear surface approximation problem is defined as: given a set S of points uniformly sampled from a vibrate function f(x,y) on a rectangular grid of dimension W X H, find a minimum triangular mesh approximating the surface with vertices anchored at a subset S' of S, such that the deviation at any sample point is within a given bound of (epsilon) > 0. The algorithm deploys a multi- agent resource planning approach to achieve adaptive, accurate and concise piecewise linear approximation using the L-(infinity) norm. The resulting manifold triangular mesh can be directly used as 3D rendering model for visualization with controllable and guaranteed quality. Due to this dual optimality, the algorithm achieves both storage efficiency and visual quality. The error control scheme further facilitates the construction of models in multiple levels of details, which is desirable in animation and virtual reality moving scenes. Experiments with various benchmark range images form smooth functional surfaces to satellite terrain images yield succinct, accurate and visually pleasant triangular meshes. Furthermore, the independence and multiplicity of agents suggest a natural parallelism for triangulation computation, which provides a promising solution for the real-time exploration of large data sets.
Solutions to the Triangular Bicycle Flags Problem
Hartweg, Kim
2005-01-01
Students in a fifth-grade general education class and a second-grade gifted class participated in the Triangular Bicycle Flags problem. The results indicated that providing students with geometric experiences at the correct van Hiele level is necessary for helping students move from one level of understanding to the next.
Basic Employability Skills: A Triangular Design Approach
Rosenberg, Stuart; Heimler, Ronald; Morote, Elsa-Sofia
2012-01-01
Purpose: This paper seeks to examine the basic employability skills needed for job performance, the reception of these skills in college, and the need for additional training in these skills after graduation. Design/methodology/approach: The research was based on a triangular design approach, in which the attitudes of three distinct groups--recent…
Wang, Yanlan; Deyris, Pierre-Alexandre; Caneque, Tatiana; Blanchard, Florent; Li, Yanling; Bigi, Franca; Maggi, Raimondo; Blanchard, Sebastien; Maestri, Giovanni; Malacria, Max
2015-08-24
A simple synthetic method allows the one-pot assembly of C3 -symmetric, 44-core-valence-electron, triangular Pd or Pt clusters and their heterobimetallic mixed Pd/Pt analogues. These mixed metal complexes are the first examples of stable triangular all-metal heteroaromatics. In contrast to traditional heteroaromatic molecules formed combining main-group elements, they actually retain structural and electronic features of their homonuclear analogues.
Linear Maps Preserving Idempotency of Products of Matrices on Upper Triangular Matrix Algebras
Institute of Scientific and Technical Information of China (English)
QI JING; JI GUO-XING
2009-01-01
. Let Tn be the algebra of all n × n complex upper triangular matrices. We give the concrete forms of linear injective maps on Tn which preserve the nonzero idempotency of either products of two matrices or triple Jordan products of two matrices.
Indian Academy of Sciences (India)
Santosh K Sahoo
2015-12-01
A relative synthetic strategy toward intermolecular oxidative C−Chalcogen bond formation of alkanes has been illustrated using both Cu(II) assisted Cu(II) free conditions. This led to construction of a comparative study of hydrocarbon benzylic and 2°/3°-cycloalkyl moieties bond sulfenylation and selenation protocol by the chalcogen sources, particularly sulfur and selenium, respectively. In addition, this protocol disclosed the auspicious formation of sp3C−S coupling products over leading the sp3C−N coupling products by using 2-mercaptobenzothiazole (MBT) substrates.
Transport Properties for Triangular Barriers in Graphene
Mouhafid, Abderrahim El; Jellal, Ahmed
2013-01-01
We theoretically study the electronic transport properties of Dirac fermions through one and double triangular barriers in graphene. Using the transfer matrix method, we determine the transmission, conductance and Fano factor. They are obtained to be various parameters dependent such as well width, barrier height and barrier width. Therefore, different discussions are given and comparison with the previous significant works is done. In particular, it is shown that at Dirac point the Dirac fer...
Vertex-Atom-Dependent Rectification in Triangular h-BNC/Triangular Graphene Heterojunctions
Wang, Lihua; Zhao, Jianguo; Zhang, Zizhen; Ding, Bingjun; Guo, Yong
2016-08-01
First-principles calculations have shown dramatically unexpected rectifying regularities in particular heterojunction configurations with triangular hexagonal boron-nitride-carbon ( h-BNC) and triangular graphene (TG) sandwiched between two armchair graphene nanoribbon electrodes. When the triangular h-BNC and TG are linked by vertex atoms of nitrogen and carbon (boron and carbon), forward (reverse) rectifying performance can be observed. Moreover, for a certain linking mode, the larger the elemental proportion p (where p = N_{{{boron}} + {{nitrogen}}} /N_{{{boron}} + {{nitrogen}} + {{carbon}}} ) in the h-BNC, the larger the ratio for forward (reverse) rectification. A mechanism for these rectification behaviors is suggested. The findings provide insights into control of rectification behaviors in TG-based nanodevices.
Ledesma, Gabriela N; Anxolabéhère-Mallart, Elodie; Rivière, Eric; Mallet-Ladeira, Sonia; Hureau, Christelle; Signorella, Sandra R
2014-03-01
Two new tri-Mn(III) complexes of general formula [Mn3L2(μ-OH)(OAc)]ClO4 (H3L = 1-[N-(2-pyridylmethyl),N-(2-hydroxybenzyl)amino]-3-[N'-(2-hydroxybenzyl),N'-(4-X-benzyl)amino]propan-2-ol; 1ClO4, X = Me; 2ClO4, X = H) have been prepared and characterized. X-ray diffraction analysis of 1ClO4 reveals that the complex cation possesses a Mn3(μ-alkoxo)2(μ-hydroxo)(μ-phenoxo)(4+) core, with the three Mn atoms bound to two fully deprotonated N3O3 chelating L(3-), one exogenous acetato ligand, and one hydroxo bridge, the structure of which is retained upon dissolution in acetonitrile or methanol. The three Mn atoms occupy the vertices of a nearly isosceles triangle (Mn1···Mn3 = 3.6374(12) Å, Mn2···Mn3 3.5583(13) Å, and Mn1···Mn2 3.2400(12) Å), with one substitution-labile site on the apical Mn ion occupied by terminally bound monodentate acetate. Temperature-dependent magnetic susceptibility studies indicate the presence of predominant antiferromagnetic intramolecular interactions between Mn(III) ions in 1ClO4. Complexes 1ClO4 and 2ClO4 decompose H2O2 at comparable rates upon initial binding of peroxide through acetate substitution, with retention of core structure during catalysis. Kinetic and spectroscopic studies suggest that these complexes employ the [Mn-(μ-oxo/aquo)-Mn](4+) moiety to activate peroxide, with the additional (μ-alkoxo)(μ-phenoxo)Mn(μ-alkoxo) metallobridge carrying out a structural function.
Theory of a triangular micro-robot
Vladimirov, Vladimir A
2012-01-01
In this paper we study the self-propulsion of a triangular micro-robot (or triangle-robot) which consists of three spheres connected by three rods; the rods' lengths are changing independently and periodically. Using the asymptotic procedure containing the two-timing method and distinguished limit arguments, we obtain analytic expressions for self-propulsion velocity the angular velocity. Our calculations show that a triangle-robot rotates with constant angular velocity around its centroid, while the centroid moves in a circle. The important special case of zero angular velocity represents rectilinear translational self-propulsion with constant velocity.
An Improved Triangular Element With Drilling Rotations
DEFF Research Database (Denmark)
Damkilde, Lars; Grønne, Mikael
2002-01-01
A new plane element with rotational degrees in the corner nodes is presented. The element has 12 degrees of freedom and the only difference from the well-known Linear Strain Triangular (LST) element is that the displacements perpendicular to the element sides in the mid-side nodes are replaced by...... rotations in the corner nodes. Compared to Allman's plane element which was the first succesfull implementation of drilling rotations the proposed element has extra displacements in the mid-side nodes parallel to the element sides. The performance should therefore be better and closer to the LST...
Effective Medium Theory of Filamentous Triangular Lattice
Mao, Xiaoming; Stenull, Olaf; Lubensky, T. C.
2011-01-01
We present an effective medium theory that includes bending as well as stretching forces, and we use it to calculate mechanical response of a diluted filamentous triangular lattice. In this lattice, bonds are central-force springs, and there are bending forces between neighboring bonds on the same filament. We investigate the diluted lattice in which each bond is present with a probability $p$. We find a rigidity threshold $p_b$ which has the same value for all positive bending rigidity and a...
Use of dermoscopy in the diagnosis of temporal triangular alopecia *
de Campos, Jullyene Gomes; Oliveira, Cláudia Marina Puga Barbosa; Romero, Sandra Adolfina Reyes; Klein, Ana Paula; Akel, Patricia Bandeira de Melo; Pinto, Giselle Martins
2015-01-01
Temporal triangular alopecia, also referred as congenital triangular alopecia, is an uncommon dermatosis of unknown etiology. It is characterized by a non-scarring, circumscribed alopecia often located unilaterally in the frontotemporal region. It usually emerges at ages 2-9 years. Alopecia areata is the main differential diagnosis, especially in atypical cases. Dermoscopy is a noninvasive procedure that helps distinguish temporal triangular alopecia from aloepecia areata. Such procedure prev...
Context-free Grammars for Triangular Arrays
Institute of Scientific and Technical Information of China (English)
Robert X. J. HAO; Larry X. W. WANG; Harold R. L. YANG
2015-01-01
We consider context-free grammars of the form G={f →fb1+b2+1ga1+a2, g→fb1ga1+1}, where ai and bi are integers subject to certain positivity conditions. Such a grammar G gives rise to triangular arrays {T (n, k)}0≤k≤n satisfying a three-term recurrence relation. Many combinatorial sequences can be generated in this way. Let Tn(x)=? nk=0 T (n, k)xk. Based on the diff erential operator with respect to G, we define a sequence of linear operators Pn such that Tn+1(x)=Pn(Tn(x)). Applying the characterization of real stability preserving linear operators on the multivariate polynomials due to Borcea and Bra¨nd´en, we obtain a necessary and suﬃ cient condition for the operator Pn to be real stability preserving for any n. As a consequence, we are led to a suﬃ cient condition for the real-rootedness of the polynomials defined by certain triangular arrays, obtained by Wang and Yeh. Moreover, as special cases we obtain grammars that lead to identities involving the Whitney numbers and the Bessel numbers.
Kondo effects in triangular triple quantum dots
Oguri, Akira; Numata, Takahide; Nisikawa, Yunori; Hewson, A. C.
2009-03-01
We study the conductance through a triangular triple quantum dot, which is connected to two noninteracting leads, using the numerical renormalization group (NRG). It is found that the system shows a variety of Kondo effects depending on the filling of the triangle. The SU(4) Kondo effect occurs at half-filling, and a sharp conductance dip due to a phase lapse appears in the gate-voltage dependence. Furthermore, when four electrons occupy the three sites on average, a local S=1 moment, which is caused by the Nagaoka mechanism, is induced along the triangle. The temperature dependence of the entropy and spin susceptibility of the triangle shows that this moment is screened by the conduction electrons via two separate stages at different temperatures. The two-terminal and four-terminal conductances show a clear difference at the gate voltages, where the SU(4) or the S=1 Kondo effects occur[1]. We will also discuss effects of deformations of the triangular configuration, caused by the inhomogeneity in the inter-dot couplings and in the gate voltages. [4pt] [1] T.Numata, Y.Nisikawa, A.Oguri, and A.C.Hewson: arXiv:0808.3496.
Ultracold quantum gases in triangular optical lattices
Becker, C; Kronjäger, J; Dörscher, S; Bongs, K; Sengstock, K
2009-01-01
Over the last years the exciting developments in the field of ultracold atoms confined in optical lattices have led to numerous theoretical proposals devoted to the quantum simulation of problems e.g. known from condensed matter physics. Many of those ideas demand for experimental environments with non-cubic lattice geometries. In this paper we report on the implementation of a versatile three-beam lattice allowing for the generation of triangular as well as hexagonal optical lattices. As an important step the superfluid-Mott insulator (SF-MI) quantum phase transition has been observed and investigated in detail in this lattice geometry for the first time. In addition to this we study the physics of spinor Bose-Einstein condensates (BEC) in the presence of the triangular optical lattice potential, especially spin changing dynamics across the SF-MI transition. Our results suggest that below the SF-MI phase transition, a well-established mean-field model describes the observed data when renormalizing the spin-d...
Ultracold quantum gases in triangular optical lattices
International Nuclear Information System (INIS)
Over recent years, exciting developments in the field of ultracold atoms confined in optical lattices have led to numerous theoretical proposals devoted to the quantum simulation of problems e.g. known from condensed matter physics. Many of those ideas demand experimental environments with non-cubic lattice geometries. In this paper, we report on the implementation of a versatile three-beam lattice allowing for the generation of triangular as well as hexagonal optical lattices. As an important step, the superfluid-Mott insulator (SF-MI) quantum phase transition has been observed and investigated in detail in this lattice geometry for the first time. In addition to this, we study the physics of spinor Bose-Einstein condensates (BEC) in the presence of the triangular optical lattice potential, especially spin changing dynamics across the SF-MI transition. Our results suggest that, below the SF-MI phase transition, a well-established mean-field model describes the observed data when renormalizing the spin-dependent interaction. Interestingly, this opens up new perspectives for a lattice-driven tuning of a spin dynamics resonance occurring through the interplay of the quadratic Zeeman effect and spin-dependent interaction. Finally, we discuss further lattice configurations that can be realized with our setup.
Ultracold quantum gases in triangular optical lattices
Energy Technology Data Exchange (ETDEWEB)
Becker, C; Soltan-Panahi, P; Doerscher, S; Sengstock, K [Institut fuer Laserphysik, Universitaet Hamburg, Hamburg D-22761 (Germany); Kronjaeger, J; Bongs, K, E-mail: cbecker@physnet.uni-hamburg.d [MUARC, School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)
2010-06-15
Over recent years, exciting developments in the field of ultracold atoms confined in optical lattices have led to numerous theoretical proposals devoted to the quantum simulation of problems e.g. known from condensed matter physics. Many of those ideas demand experimental environments with non-cubic lattice geometries. In this paper, we report on the implementation of a versatile three-beam lattice allowing for the generation of triangular as well as hexagonal optical lattices. As an important step, the superfluid-Mott insulator (SF-MI) quantum phase transition has been observed and investigated in detail in this lattice geometry for the first time. In addition to this, we study the physics of spinor Bose-Einstein condensates (BEC) in the presence of the triangular optical lattice potential, especially spin changing dynamics across the SF-MI transition. Our results suggest that, below the SF-MI phase transition, a well-established mean-field model describes the observed data when renormalizing the spin-dependent interaction. Interestingly, this opens up new perspectives for a lattice-driven tuning of a spin dynamics resonance occurring through the interplay of the quadratic Zeeman effect and spin-dependent interaction. Finally, we discuss further lattice configurations that can be realized with our setup.
A METHOD FOR STIFFNESS MATRIX OF TRIANGULAR TORUS ELEMENT
Directory of Open Access Journals (Sweden)
Durmuş GÜNAY
1996-01-01
Full Text Available The matrices of constants for the stiffness matrices of triangular torus elements family are generated on computer by using the expression given in literature. After the matrices are generated once, it is easy to obtain the stiffness matrices for all member of family of triangular torus elements without need for numerical integration.
The Geometric Continuity of Rational Bezier Triangular Surfaces
Institute of Scientific and Technical Information of China (English)
田捷
1991-01-01
The problems of geometric continuity for rational Bezier surfaces are discussed.Concise conditions of first order and second order geometric continuity for rational triangular bezier surfaces are given.Meanwhile,a geometric condition for smoothness between adjacent rational bezier surfaces and the transformation formulae between rational triangular patches and rational rectangular patches are obtained.
Triangular model integrating clinical teaching and assessment.
Abdelaziz, Adel; Koshak, Emad
2014-01-01
Structuring clinical teaching is a challenge facing medical education curriculum designers. A variety of instructional methods on different domains of learning are indicated to accommodate different learning styles. Conventional methods of clinical teaching, like training in ambulatory care settings, are prone to the factor of coincidence in having varieties of patient presentations. Accordingly, alternative methods of instruction are indicated to compensate for the deficiencies of these conventional methods. This paper presents an initiative that can be used to design a checklist as a blueprint to guide appropriate selection and implementation of teaching/learning and assessment methods in each of the educational courses and modules based on educational objectives. Three categories of instructional methods were identified, and within each a variety of methods were included. These categories are classroom-type settings, health services-based settings, and community service-based settings. Such categories have framed our triangular model of clinical teaching and assessment.
Synthesis and morphology of triangular pyramid-shaped puerarin microparticle with nanostructure
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
A type of triangular pyramid-shaped microparticles of puerarin was synthesized by using oil-in-oil microemulsion approach which is simple and economical under the action of copper substrate.The pyramid-shaped microparticles would be made up of deposit of nanospheres or nanorods and have two significant characters.One is its complex surface morphology like coral reef.The other is a lot of nanopores in existence in the microparticle body.Two possible formation routes were speculated.
Triangularity effects on the collisional diffusion for elliptic tokamak plasma
International Nuclear Information System (INIS)
In this conference the effect of ellipticity and triangularity will be analyzed for axisymmetric tokamak in the collisional regime. Analytic forms for the magnetic field cross sections are taken from those derived recently by other authors [1,2]. Analytical results can be obtained in elliptic plasmas with triangularity by using an special system of tokamak coordinates recently published [3-5]. Our results show that triangularities smaller than 0.6, increases confinement for ellipticities in the range 1.2 to 2. This behavior happens for negative and positive triangularities; however this effect is stronger for positive than for negative triangularities. The maximum diffusion velocity is not obtained for zero triangularity, but for small negative triangularities. Ellipticity is also very important in confinement, but the effect of triangularity seems to be more important. High electric inductive field increases confinement, though this field is difficult to modify once the tokamak has been built. The analytic form of the current produced by this field is like that of a weak Ware pinch with an additional factor, which weakens the effect by an order of magnitude. The dependence of the triangularity effect with the Shafranov shift is also analyzed. References 1. - L. L. Lao, S. P. Hirshman, and R. M. Wieland, Phys. Fluids 24, 1431 (1981) 2. - G. O. Ludwig, Plasma Physics Controlled Fusion 37, 633 (1995) 3. - P. Martin, Phys. Plasmas 7, 2915 (2000) 4. - P. Martin, M. G. Haines and E. Castro, Phys. Plasmas 12, 082506 (2005) 5. - P. Martin, E. Castro and M. G. Haines, Phys. Plasmas 12, 102505 (2005)
Adaptive triangular mesh coarsening with centroidal Voronoi tessellations
Institute of Scientific and Technical Information of China (English)
Zhen-yu SHU; Guo-zhao WANG; Chen-shi DONG
2009-01-01
We present a novel algorithm for adaptive triangular mesh coarsening. The algorithm has two stages. First, the input triangular mesh is refined by iteratively applying the adaptive subdivision operator that performs a so-called red-green split.Second, the refined mesh is simplified by a clustering algorithm based on centroidal Voronoi tessellations (CVTs). The accuracy and good quality of the output triangular mesh are achieved by combining adaptive subdivision and the CVTs technique. Test results showed the mesh coarsening scheme to be robust and effective. Examples are shown that validate the method.
A New Triangular Flat Shell Element With Drilling Rotations
DEFF Research Database (Denmark)
Damkilde, Lars
2008-01-01
A new flat triangular shell element has been developed based on a newly developed triangular plate bending element by the author and a new triangular membrane element with drilling degrees of freedom. The advantage of the drilling degree of freedom is that no special precautions have to be made...... in connecting with assembly of elements. Due to the drilling rotations all nodal degrees of freedom have stiffness, and therefore no artificial suppression of degrees of freedom are needed for flat or almost flat parts of the shell structure....
Logical, algebraic, analytic and probabilistic aspects of triangular norms
Klement, Erich Peter
2005-01-01
This volume gives a state of the art of triangular norms which can be used for the generalization of several mathematical concepts, such as conjunction, metric, measure, etc. 16 chapters written by leading experts provide a state of the art overview of theory and applications of triangular norms and related operators in fuzzy logic, measure theory, probability theory, and probabilistic metric spaces.Key Features:- Complete state of the art of the importance of triangular norms in various mathematical fields- 16 self-contained chapters with extensive bibliographies cover both the theoretical ba
Optimization of Multi-band Rectangular-Triangular Slotted Antenna
Directory of Open Access Journals (Sweden)
K.swetha,
2015-03-01
Full Text Available A multi-band microstrip patch antenna is developed and presented in this paper. The radiating elements in this antenna are composed of rectangular and triangular slots. These slots are engraved in the rectangular and triangular patch, joined together in one structure, and by single probe feed. The rectangular and triangular slots make the antenna to operate at multiband with relatively high gain. Therefore, this antenna can be used for wireless communication applications like WLAN, WiMax and radar system applications.
Some Observations on Characteristics of China-U.S.-Russia Triangular Relationship
Institute of Scientific and Technical Information of China (English)
Li; Xing
2014-01-01
The China-U.S.-Russia triangular relationship emerged in the 1970s~90s, and is still in existence, but only the era environment and conditions, the compared strength between three countries, the impact scope and degree have changed. This triangular relationship is one of the world’s most complex, the most delicate and the most important. The Sino-U.S. relations and Sino-Russian relations are the most important bilateral relationships for China. As China upgrades its strategic and coordinate partnership with Russia, it also energetically promotes strategic-oriented relationship with the United States, namely, in the aspect of high politics, developing the strategic and coordinate relations with Russia, while in the aspect of low politics, developing mutually beneficial and win-win cooperation with the United States.
Tomographic particle image velocimetry over a triangular prism in unidirectional flows
Sou, In Mei; Calantoni, Joseph
2011-11-01
Using tomographic particle image velocimetry (Tomo-PIV), the full three-dimensional-three-component (3D-3C) flow structure and turbulence characteristics over a triangular prism in a recirculating water tunnel were investigated. Here we present preliminary results from a new Tomo-PIV system for subcritical Froude number flows. Large-scale vortex shedding from the tip of the triangular prism is observed. Results of coherent structure organization analyzed by 3D vorticity calculation will be presented. Using the full 3D-3C instantaneous velocity field, turbulent kinetic energy is directly evaluated without any of the assumptions often needed for 2D PIV measurements. Details of the experimental setup including a unique device designed to perform our Tomo-PIV volume calibration will be discussed. We perform an in-depth turbulent kinetic energy budget and explore the feasibility of extending the measurement technique to other complex flows.
A New Triangular Spectral Element Method I: Implementation and Analysis on a Triangle
Samson, Michael Daniel; Wang, Li-Lian
2012-01-01
This paper serves as our first effort to develop a new triangular spectral element method (TSEM) on unstructured meshes, using the rectangle-triangle mapping proposed in the conference note [21]. Here, we provide some new insights into the originality and distinctive features of the mapping, and show that this transform only induces a logarithmic singularity, which allows us to devise a fast, stable and accurate numerical algorithm for its removal. Consequently, any triangular element can be treated as efficiently as a quadrilateral element, which affords a great flexibility in handling complex computational domains. Benefited from the fact that the image of the mapping includes the polynomial space as a subset, we are able to obtain optimal $L^2$- and $H^1$-estimates of approximation by the proposed basis functions on triangle. The implementation details and some numerical examples are provided to validate the efficiency and accuracy of the proposed method. All these will pave the way for developing an unstr...
Electro-osmotic flows inside triangular microchannels
International Nuclear Information System (INIS)
This work presents a numerical investigation of both pure electro-osmotic and combined electro-osmotic/pressure-driven flows inside triangular microchannels. A finite element analysis has been adopted to solve the governing equations for the electric potential and the velocity field, accounting for a finite thickness of the electric double layer. The influence of non-dimensional parameters such as the aspect ratio of the cross-section, the electrokinetic diameter and the ratio of the pressure force to the electric force on the flow behavior has been investigated. Numerical results point out that the velocity field is significantly influenced by the aspect ratio of the cross section and the electrokinetic diameter. More specifically, the aspect ratio plays an important role in determining the maximum volumetric flow rate, while the electrokinetic diameter is crucial to establishing the range of pressures that may be sustained by the electro-osmotic flow. Numerical results are also compared with two correlations available in the literature which enable to assess the volumetric flow rate and the pressure head for microchannels featuring a rectangular, a trapezoidal or an elliptical cross-section.
Triangular model integrating clinical teaching and assessment
Directory of Open Access Journals (Sweden)
Abdelaziz A
2014-03-01
Full Text Available Adel Abdelaziz,1,2 Emad Koshak3 1Medical Education Development Unit, Faculty of Medicine, Al Baha University, Al Baha, Saudi Arabia; 2Medical Education Department, Faculty of Medicine, Suez Canal University, Egypt; 3Dean and Internal Medicine Department, Faculty of Medicine, Al Baha University, Al Baha, Saudi Arabia Abstract: Structuring clinical teaching is a challenge facing medical education curriculum designers. A variety of instructional methods on different domains of learning are indicated to accommodate different learning styles. Conventional methods of clinical teaching, like training in ambulatory care settings, are prone to the factor of coincidence in having varieties of patient presentations. Accordingly, alternative methods of instruction are indicated to compensate for the deficiencies of these conventional methods. This paper presents an initiative that can be used to design a checklist as a blueprint to guide appropriate selection and implementation of teaching/learning and assessment methods in each of the educational courses and modules based on educational objectives. Three categories of instructional methods were identified, and within each a variety of methods were included. These categories are classroom-type settings, health services-based settings, and community service-based settings. Such categories have framed our triangular model of clinical teaching and assessment. Keywords: curriculum development, teaching, learning, assessment, apprenticeship, community-based settings, health service-based settings
Final critical habitat for Triangular Kidneyshell (Ptychobranchus greenii)
US Fish and Wildlife Service, Department of the Interior — This Polygon shapefile of critical habitat for the Triangular Kidneyshell (Ptychobranchus greenii) based on the description provided in the Federal Register.
BOUNDING PYRAMIDS AND BOUNDING CONES FOR TRIANGULAR BEZIER SURFACES
Institute of Scientific and Technical Information of China (English)
Jian-song Deng; Fa-lai Chen; Li-li Wang
2000-01-01
This paper describes practical approaches on how to construct bounding pyramids and bounding cones for triangular Bézier surfaces. Examples are provided to illustrate the process of construction and comparison is made between various surface bounding volumes. Furthermore, as a starting point for the construction,we provide a way to compute hodographs of triangular Bézier surfaces and improve the algorithm for computing the bounding cone of a set of vectors.
Triangular nanobeam photonic cavities in single crystal diamond
Bayn, Igal; Meyler, Boris; Salzman, Joseph; Kalish, Rafi
2011-01-01
Diamond photonics provides an attractive architecture to explore room temperature cavity quantum electrodynamics and to realize scalable multi-qubit computing. Here we review the present state of diamond photonic technology. The design, fabrication and characterization of a novel triangular cross section nanobeam cavity produced in a single crystal diamond is demonstrated. The present cavity design, based on a triangular cross section allows vertical confinement and better signal collection e...
Seven Means, Generalized Triangular Discrimination, and Generating Divergence Measures
Tameja, Inder Jeet
2012-01-01
From geometrical point of view, Eve (2003) studied seven means. These means are Harmonic, Geometric, Arithmetic, Heronian, Contra-harmonic, Root-mean square and Centroidal mean. We have considered for the first time a new measure calling generalized triangular discrimination. Inequalities among non-negative differences arising due to seven means and particular cases of generalized triangular discrimination are considered. Some new generating measures and their exponential representations are also presented.
A Class of New Metrics Based on Triangular Discrimination
Directory of Open Access Journals (Sweden)
Guoxiang Lu
2015-07-01
Full Text Available In the field of information theory, statistics and other application areas, the information-theoretic divergences are used widely. To meet the requirement of metric properties, we introduce a class of new metrics based on triangular discrimination which are bounded. Moreover, we obtain some sharp inequalities for the triangular discrimination and other information-theoretic divergences. Their asymptotic approximation properties are also involved.
Approximating Runge-Kutta matrices by triangular matrices
Hoffmann, W.; Swart, de, P.
1997-01-01
The implementation of implicit Runge-Kutta methods requires the solution of large systems of non-linear equations. Normally these equations are solved by a modified Newton process, which can be very expensive for problems of high dimension. The recently proposed triangularly implicit iteration methods for ODE-IVP solvers [HSw95] substitute the Runge-Kutta matrix A in the Newton process for a triangular matrix T that approximates A, hereby making the method suitable for parallel implementation...
On the Eigenvalues and Eigenvectors of Block Triangular Preconditioned Block Matrices
Pestana, Jennifer
2014-01-01
Block lower triangular matrices and block upper triangular matrices are popular preconditioners for 2×2 block matrices. In this note we show that a block lower triangular preconditioner gives the same spectrum as a block upper triangular preconditioner and that the eigenvectors of the two preconditioned matrices are related. © 2014 Society for Industrial and Applied Mathematics.
Bhattacharya, Kisholoy; Maity, Manoranjan; Abtab, Sk Md Towsif; Majee, Mithun Chandra; Chaudhury, Muktimoy
2013-08-19
A new family of trinuclear homo- and heterometal complexes with a triangular [V(V)O-MO-V(V)O] (M = V(IV), 1 and 2; Re(V), 3] all-oxido-metal core have been synthesized following a single-pot protocol using compartmental Schiff-base ligands, N,N'-bis(3-hydroxysalicylidene)-diiminoalkanes/arene (H4L(1)-H4L(3)). The upper compartment of these ligands with N2O2 donor combination (Salen-type) contains either a V(IV) or a Re(V) center, while the lower compartment with O4 donor set accommodates two V(V) centers, stabilized by a terminal and a couple of bridging methoxido ligands. The compounds have been characterized by single-crystal X-ray diffraction analyses, which reveal octahedral geometry for all three metal centers in 1-3. Compound 1 crystallizes in a monoclinic space group P2(1)/c, while both 2 and 3 have more symmetric structures with orthorhombic space group Pnma that renders the vanadium(V) centers in these compounds exactly identical. In DMF solution, compound 1 displays an 8-line EPR at room temperature with and values of 1.972 and 86.61 × 10(-4) cm(-1), respectively. High-resolution X-ray photoelectron spectrum (XPS) of this compound shows a couple of bands at 515.14 and 522.14 eV due to vanadium 2p(3/2) and 2p(1/2) electrons in the oxidation states +5 and +4, respectively. All of these, together with bond valence sum (BVS) calculation, confirm the trapped-valence nature of mixed-oxidation in compounds 1 and 2. Electrochemically, compound 1 undergoes two one-electron oxidations at E(1/2) = 0.52 and 0.83 V vs Ag/AgCl reference. While the former is due to a metal-based V(IV/V) oxidation, the latter one at higher potential is most likely due to a ligand-based process involving one of the catecholate centers. A larger cavity size in the upper compartment of the ligand H4L(3) is spacious enough to accommodate Re(V) with larger size to generate a rare type of all-oxido heterotrimetallic compound (3) as established by X-ray crystallography. PMID:23898782
Chemical compounds isolated from Talinum triangulare (Portulacaceae).
de Oliveira Amorim, Ana Paula; de Carvalho, Almir Ribeiro; Lopes, Norberto Peporine; Castro, Rosane Nora; de Oliveira, Marcia Cristina Campos; de Carvalho, Mário Geraldo
2014-10-01
This first phytochemical study of Talinum triangulare Leach (Portulacaceae), also known as 'cariru', which is a commonly consumed food in Northern Brazil, allowed the isolation and structural determination of four new compounds: one acrylamide, 3-N-(acryloyl, N-pentadecanoyl) propanoic acid (5), and three new phaeophytins named (15(1)S, 17R, 18R)-Ficuschlorin D acid (3(1),3(2)-didehydro-7-oxo-17(3)-O-phytyl-rhodochlorin-15-acetic acid), (13), Talichorin A (17R, 18R)-phaeophytin b-15(1)-hidroxy, 15(2),15(3)-acetyl-13(1)-carboxilic acid (14), and (15(1)S, 17R, 18R)-phaeophytin b peroxylactone or (15(1)S, 17R, 18R)-hydroperoxy-ficuschlorin D (16), together with twelve known compounds, including four phaeophytins (11,12, 15 and 17). The structures of the compounds were established on the basis of 1D and 2D NMR, IR, HRESI-MS spectra, including GC-MS, and HPLC-UV analysis, as well as comparisons with the literature data. The CD spectra data analysis were used to define the absolute configuration of phaeophytins 12 (13(2)R, 17R, 18R)-13(2)-hydroxyphaeophytin a, 13 and 16, 15 (15(1)S, 17R, 18R)-3(1),3(2)-didehydro-15(1)-hydroxyrhodochlorin-15-acetic acid δ-lactone-15(2)-methyl-17(3)-phytyl ester and 17 (17R, 18R)-purpurin 18-phytyl ester. PMID:24799228
Institute of Scientific and Technical Information of China (English)
Zhensong Chen; Shenghua Xiong; Yanlai Li; Kwai-Sang Chin
2015-01-01
In order to measure the uncertain information of a type-2 intuitionistic fuzzy set (T2IFS), an entropy measure of T2IFS is presented by using the constructive principles. The proposed entropy measure is also proved to satisfy al of the constructive principles. Further, a novel concept of the type-2 triangular in-tuitionistic trapezoidal fuzzy set (T2TITrFS) is developed, and a geometric interpretation of the T2TITrFS is given to comprehend it completely or correctly in a more intuitive way. To deal with a more general uncertain complex system, the constructive principles of an entropy measure of T2TITrFS are therefore proposed on the basis of the axiomatic definition of the type-2 intuitionisic fuzzy entropy measure. This paper elicits a formula of type-2 triangular intuitionistic trapezoidal fuzzy entropy and verifies that it does sa-tisfy the constructive principles. Two examples are given to show the efficiency of the proposed entropy of T2TITrFS in describing the uncertainty of the type-2 intuitionistic fuzzy information and il ustrate its application in type-2 triangular intuitionistic trapezodial fuzzy decision making problems.
Elliptic and Triangular flow in asymmetric heavy-ion collisions
Haque, Md Rihan; Mohanty, Bedangadas
2011-01-01
We present a study of the elliptic (v2) and triangular (v3) flow and their corresponding eccentricity fluctuations for asymmetric (Au+Ag, Au+Cu and Au+Si) collisions at \\sqrt_NN = 200 GeV. These are compared to the corresponding results from symmetric (Au+Au and Cu+Cu) collisions at the same energy. The study which is carried out using a multi-phase transport (AMPT) model shows that triangularity (\\epsilon_3), fluctuations in triangularity and v3 do not show much variation for the different colliding ion sizes studied. However the eccentricity (\\epsilon_2), fluctuations in eccentricity and v2 shows a strong dependence on colliding ion size for a given number of participating nucleons. Our study thus indicates that asymmetric heavy-ion collisions could be used to constrain models dealing with flow fluctuations in heavy-ion collisions.
Field-design optimization with triangular heliostat pods
Domínguez-Bravo, Carmen-Ana; Bode, Sebastian-James; Heiming, Gregor; Richter, Pascal; Carrizosa, Emilio; Fernández-Cara, Enrique; Frank, Martin; Gauché, Paul
2016-05-01
In this paper the optimization of a heliostat field with triangular heliostat pods is addressed. The use of structures which allow the combination of several heliostats into a common pod system aims to reduce the high costs associated with the heliostat field and therefore reduces the Levelized Cost of Electricity value. A pattern-based algorithm and two pattern-free algorithms are adapted to handle the field layout problem with triangular heliostat pods. Under the Helio100 project in South Africa, a new small-scale Solar Power Tower plant has been recently constructed. The Helio100 plant has 20 triangular pods (each with 6 heliostats) whose positions follow a linear pattern. The obtained field layouts after optimization are compared against the reference field Helio100.
Investigates on Aerodynamic Characteristics of Projectile with Triangular Cross Section
Institute of Scientific and Technical Information of China (English)
YI Wen-jun; WANG Zhong-yuan; LI Yan; QIAN Ji-sheng
2009-01-01
The aerodynamic characteristics of projectiles with triangular and circular cross sections are investigated respectively by use of free-flight experiment. Processed the experiment data, curves of flight velocity variation and nutation of both projectiles are obtained, based on the curves, their aerodynamic force and moment coefficients are found out by data fitting, and their aerodynamic performances are compared and analyzed. Results show that the projectile with triangular cross section has smaller resistance, higher lift-drag ratio, better static stability, higher stability capability and more excellent maneuverability than those of the projectile with circular cross section, therefore it can be used in the guided projectiles; under lower rotation speed, the triangular section projectile has greater Magnus moment leading to bigger projectile distribution.
Pattern design on 3D triangular garment surfaces
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
This paper focuses on a pattern design method for a 3D triangular garment surface. Firstly, some definitions of 3D style lines are proposed for designing the boundaries of patterns as drawing straight lines or splines on the triangular surface.Additionally some commonly used style lines are automatically generated to enhance design efficiency. Secondly, after style lines are preprocessed, a searching method is presented for quickly obtaining the boundaries and patches of a pattern on the 3D triangular surface. Finally a new pattern design reuse method is introduced by encoding/decoding the style line information. After style lines are encoded, the pattern design information can be saved in a pattern template and when decoding this template on a new garment surface, it automates the pattern generation for made-to-measure apparel products.
Andreani, L C
2006-01-01
According to a recent proposal [S. Takayama et al., Appl. Phys. Lett. 87, 061107 (2005)], the triangular lattice of triangular air holes may allow to achieve a complete photonic band gap in two-dimensional photonic crystal slabs. In this work we present a systematic theoretical study of this photonic lattice in a high-index membrane, and a comparison with the conventional triangular lattice of circular holes, by means of the guided-mode expansion method whose detailed formulation is described here. Photonic mode dispersion below and above the light line, gap maps, and intrinsic diffraction losses of quasi-guided modes are calculated for the periodic lattice as well as for line- and point-defects defined therein. The main results are summarized as follows: (i) the triangular lattice of triangular holes does indeed have a complete photonic band gap for the fundamental guided mode, but the useful region is generally limited by the presence of second-order waveguide modes; (ii) the lattice may support the usual p...
Universal triangular spectra in parametrically-driven systems
Energy Technology Data Exchange (ETDEWEB)
Akhmediev, Nail [Optical Sciences Group, Research School of Physics and Engineering, Institute of Advanced Studies, Australian National University, Canberra ACT 0200 (Australia); Ankiewicz, Adrian, E-mail: ana124@rsphysse.anu.edu.a [Optical Sciences Group, Research School of Physics and Engineering, Institute of Advanced Studies, Australian National University, Canberra ACT 0200 (Australia); Soto-Crespo, J.M. [Instituto de Optica, C.S.I.C., Serrano 121, 28006 Madrid (Spain); Dudley, John M. [Institut FEMTO-ST, UMR 6174 CNRS-Universite de Franche-Comte, 25030 Besancon (France)
2011-01-17
We analyse triangular spectra that appear in many branches of physics that deal with parametrically-driven systems, and give a simple theoretical analysis for them in terms of the nonlinear dynamics of multimode fields. Such spectra appear universally as a result of an exponential decay of the nonlinearly generated frequency modes of many parametrically-driven systems, and have been confirmed by recent observations of noise-driven supercontinuum generation in optical fibers. We demonstrate that such universal triangular spectra (UTS) can be well-described by the analytical expressions for the spectra of Akhmediev breather (AB) solutions at the point of maximal compression.
An Evaluation Method for Distortion Energy Parameterization of Triangular Meshes
Institute of Scientific and Technical Information of China (English)
SHI Jing; ZHAO Xiu-yang; ZHANG Cai-ming; YANG Bo
2013-01-01
Parameterization of triangle meshes is a fundamental problem for texture mapping, surface fitting, surface reconstruction, and mesh editing. The deformation of triangular meshes caused by the parameterized process is the measurement of parameterization. Traditional standard method has its limitation when evaluating mixture distortion energy parameterizations. Thus an evaluation method bases on distortion energy parameterization of triangular meshes is introduced for the limitation. The novel method employs an adaptive expression form to the mixture energy, and uses a weight factor to represent distortion energy distribution. By using this method, we can evaluate all kinds of parameterization in a uniform measurement and acquire a more intuitive and clear evaluation.
Bistable Chimera Attractors on a Triangular Network of Oscillator Populations
DEFF Research Database (Denmark)
Martens, Erik Andreas
2010-01-01
We study a triangular network of three populations of coupled phase oscillators with identical frequencies. The populations interact nonlocally, in the sense that all oscillators are coupled to one another, but more weakly to those in neighboring populations than to those in their own population....... This triangular network is the simplest discretization of a continuous ring of oscillators. Yet it displays an unexpectedly different behavior: in contrast to the lone stable chimera observed in continuous rings of oscillators, we find that this system exhibits two coexisting stable chimeras. Both chimeras are...
Partitioning a chordal graph into transitive subgraphs for parallel sparse triangular solution
Energy Technology Data Exchange (ETDEWEB)
Peyton, B.W. [Oak Ridge National Lab., TN (United States); Pothen, A. [Waterloo Univ., ON (Canada). Dept. of Computer Science; Yuan, Xiaoqing [IBM Canada Lab., North York, Ontario (Canada)
1992-12-01
A recent approach for solving sparse triangular systems of equations on massively parallel computers employs a factorization of the triangular coefficient matrix to obtain a representation of its inverse in product form. The number of general communication steps required by this approach is proportional to the number of factors in the factorization. The triangular matrix can be symmetrically permuted to minimize the number of factors over suitable classes of permutations, and thereby the complexity of the parallel algorithm can be minimized. Algorithms for minimizing the number of factors over several classes of permutations have been considered in earlier work. Let F = L+L{sup T} denote the symmetric filled matrix corresponding to a Cholesky factor L, and let G{sub F} denote the adjacency graph of F. In this paper we consider the problem of minirriizing the number of factors over all permutations which preserve the structure of G{sub F}. The graph model of this problem is to partition the vertices G{sub F} into the fewest transitively closed subgraphs over all perfect elimination orderings while satisfying a certain precedence relationship. The solution to this chordal graph partitioning problem can be described by a greedy scheme which eliminates a largest permissible subgraph at each step. Further, the subgraph eliminated at each step can be characterized in terms of lengths of chordless paths in the current elimination graph. This solution relies on several results concerning transitive perfect elimination orderings introduced in this paper. We describe a partitioning algorithm with {Omicron}({vert_bar}V{vert_bar} + {vert_bar}E{vert_bar}) time and space complexity.
Partitioning a chordal graph into transitive subgraphs for parallel sparse triangular solution
Energy Technology Data Exchange (ETDEWEB)
Peyton, B.W. (Oak Ridge National Lab., TN (United States)); Pothen, A. (Waterloo Univ., ON (Canada). Dept. of Computer Science); Yuan, Xiaoqing (IBM Canada Lab., North York, Ontario (Canada))
1992-12-01
A recent approach for solving sparse triangular systems of equations on massively parallel computers employs a factorization of the triangular coefficient matrix to obtain a representation of its inverse in product form. The number of general communication steps required by this approach is proportional to the number of factors in the factorization. The triangular matrix can be symmetrically permuted to minimize the number of factors over suitable classes of permutations, and thereby the complexity of the parallel algorithm can be minimized. Algorithms for minimizing the number of factors over several classes of permutations have been considered in earlier work. Let F = L+L[sup T] denote the symmetric filled matrix corresponding to a Cholesky factor L, and let G[sub F] denote the adjacency graph of F. In this paper we consider the problem of minirriizing the number of factors over all permutations which preserve the structure of G[sub F]. The graph model of this problem is to partition the vertices G[sub F] into the fewest transitively closed subgraphs over all perfect elimination orderings while satisfying a certain precedence relationship. The solution to this chordal graph partitioning problem can be described by a greedy scheme which eliminates a largest permissible subgraph at each step. Further, the subgraph eliminated at each step can be characterized in terms of lengths of chordless paths in the current elimination graph. This solution relies on several results concerning transitive perfect elimination orderings introduced in this paper. We describe a partitioning algorithm with [Omicron]([vert bar]V[vert bar] + [vert bar]E[vert bar]) time and space complexity.
A Novel VOF-Type Volume-Tracking Method for Free-Surface Flows Based on Unstructured Triangular Mesh
Institute of Scientific and Technical Information of China (English)
JI Chun-ning; WANG Yuan-zhan; WANG Jian-feng
2005-01-01
A novel VOF-type volume-tracking method for two-dimensional free-surface flows based on the unstructured triangular mesh is presented. Owing to the inherent merit of the unstructured triangular mesh in fitting curved boundaries, this method can handle the free-surface problems with complex geometries accurately and directly, without introducing any complicated boundary treatment or artificial diffusion. The method solves the volume transport equation geometrically through the Modified Lagrangian-Eulerian Re-map (MLER) method, which is applied to advective fluid volumes. Moreover, the PLIC method is adopted to give a second-order reconstructed interface approximation. To validate this method, two advection tests were performed for the establishment of the accuracy and convergence rate of the solutions. Numerical results for these complex tests provide convincing evidence for the excellent solution quality and fidelity of the method.
Triangular Clinics: The Way of The Future
Directory of Open Access Journals (Sweden)
Seyed-Moayed Alavian
2005-09-01
other created the incentive to try something totally different. The Triangular Clinics, chosen
Characterization of Lie Higher Derivations on Triangular Algebras
Institute of Scientific and Technical Information of China (English)
Xiao Fei QI
2013-01-01
Let A and B be unital rings,and M be an (A,B)-bimodule,which is faithful as a left A-module and also as a right B-module.Let U =Tri(A,M,B) be the triangular algebra.In this paper,we give some different characterizations of Lie higher derivations on U.
Selectively colorimetric detection of cysteine with triangular silver nanoprisms
Institute of Scientific and Technical Information of China (English)
Tong Wu; Yuan Fang Li; Cheng Zhi Huang
2009-01-01
Triangular silver nanoprisms were prepared and applied to make colorimetric detection of cysteine based on our findings that cysteine could lead to the blue shift of the dipole plasmon resonance absorption,but other 19 kinds of natural amino acids could not.Cysteine with a concentration 160 nmol/L can result in a color change that can be discerned with naked eyes.
Equivalence of nonlinear systems to triangular form: the singular case
Celikovsky, Sergej; Nijmeijer, Henk
1996-01-01
The problem of state equivalence of a given nonlinear system to a triangular form is considered here. The solution of this problem has been known for the regular case, i.e. when there exists a certain nested sequence of regular and involutive distributions. It is also known that in this case the cor
Triangular Numbers, Gaussian Integers, and KenKen
Watkins, John J.
2012-01-01
Latin squares form the basis for the recreational puzzles sudoku and KenKen. In this article we show how useful several ideas from number theory are in solving a KenKen puzzle. For example, the simple notion of triangular number is surprisingly effective. We also introduce a variation of KenKen that uses the Gaussian integers in order to…
On certain diophantine equations related to triangular and tetrahedral numbers
Ulas, Maciej
2008-01-01
In this paper we give solutions of certain diophantine equations related to triangular and tetrahedral numbers and propose several problems connected with these numbers. The material of this paper was presented in part at the 11th International Workshop for Young Mathematicians - NUMBER THEORY, Krak\\'{o}w, 14th-20th september 2008.
Modelonderzoek meetpunt Slenaken : "Flat - 5 triangular profile weir"
Bennink, J.; Pitlo, R.H.
1977-01-01
In de buurt van de Belgische grens werd in de Gulp te Slenaken (Zd. Limburg) door Rijkswaterstaat een meetstuw gebouwd van het type "Flat-V triangular profile weir". Een schaalmodel van de meetstuw is in Wageningen geijkt. De afvoergegevens zullen ook worden gebruikt door de "Studiegroep Gulp".
Anisotropic Adhesion Properties of Triangular-Tip-Shaped Micropillars
Kwak, Moon Kyu
2011-06-01
Directional dry adhesive microstructures consisting of high-density triangular-tip-shaped micropillars are described. The wide-tip structures allow for unique directional shear adhesion properties with respect to the peeling direction, along with relatively high normal adhesion. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
The Numerical Integration of Discrete Functions on a Triangular Element
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
With the application of Hammer integral formulas of a continuousfunction on a triangular element, the numerical integral formulas of some discrete functions on the element are derived by means of decomposition and recombination of base functions. Hammer integral formulas are the special examples of those of the paper.
A Subdivision Scheme for Rational Triangular Bezier Surfaces
Institute of Scientific and Technical Information of China (English)
胡事民
1996-01-01
An explicit formula is developed to decompose a rational triangular Bezier patch into three non-degenerate rational rectangular Bezier patches of the same degree.This formula yields a stable algorithm to compute the control vertices of those three rectangular subpatches.Some properties of the subdivision are discussed and the formula is illustrated with an example.
Directory of Open Access Journals (Sweden)
Ana Paula Oliveira Amorim
2013-07-01
Full Text Available The aim of this work is to evaluate the antioxidant activity against the radical species DPPH, the reducing capacity against Fe II ions, and the inhibitory activity on the tyrosinase enzyme of the T. triangulare. Hydromethanolic crude extract provided two fractions after the liquid/liquid partition with chloroform. The Folin-Ciocalteu method determined the total phenolic content of the crude extract (CE and the hydromethanolic fraction (Fraction 1, resulting in a concentration of 0.5853 g/100 g for Fraction 1, and 0.1400 g/100 g for the CE. Taking into account the results of the DPPH, the free radical scavenging capacity was confirmed. The formation of complexes with Fe II ions was evaluated by UV/visible spectrometry; results showed that CE has complexing power similar to the positive control (Gingko biloba extract.The inhibitory capacity of samples against the tyrosinase enzyme was determined by the oxidation of L-DOPA, providing IC50 values of 13.3 μg·mL−1 (CE and 6.6 μg·mL−1 (Fraction 1. The values indicate that Fraction 1 was more active and showed a higher inhibitory power on the tyrosinase enzyme than the ascorbic acid, used as positive control. The hydromethanolic extract of T. triangulare proved to have powerful antioxidant activity and to inhibit the tyrosinase enzyme; its potential is increased after the partition with chloroform.
Oliveira Amorim, Ana Paula; Campos de Oliveira, Márcia Cristina; de Azevedo Amorim, Thiago; Echevarria, Aurea
2013-01-01
The aim of this work is to evaluate the antioxidant activity against the radical species DPPH, the reducing capacity against Fe II ions, and the inhibitory activity on the tyrosinase enzyme of the T. triangulare. Hydromethanolic crude extract provided two fractions after the liquid/liquid partition with chloroform. The Folin-Ciocalteu method determined the total phenolic content of the crude extract (CE) and the hydromethanolic fraction (Fraction 1), resulting in a concentration of 0.5853 g/100 g for Fraction 1, and 0.1400 g/100 g for the CE. Taking into account the results of the DPPH, the free radical scavenging capacity was confirmed. The formation of complexes with Fe II ions was evaluated by UV/visible spectrometry; results showed that CE has complexing power similar to the positive control (Gingko biloba extract).The inhibitory capacity of samples against the tyrosinase enzyme was determined by the oxidation of L-DOPA, providing IC50 values of 13.3 μg·mL(-1) (CE) and 6.6 μg·mL(-1) (Fraction 1). The values indicate that Fraction 1 was more active and showed a higher inhibitory power on the tyrosinase enzyme than the ascorbic acid, used as positive control. The hydromethanolic extract of T. triangulare proved to have powerful antioxidant activity and to inhibit the tyrosinase enzyme; its potential is increased after the partition with chloroform. PMID:26784338
Oliveira Amorim, Ana Paula; Campos de Oliveira, Márcia Cristina; de Azevedo Amorim, Thiago; Echevarria, Aurea
2013-01-01
The aim of this work is to evaluate the antioxidant activity against the radical species DPPH, the reducing capacity against Fe II ions, and the inhibitory activity on the tyrosinase enzyme of the T. triangulare. Hydromethanolic crude extract provided two fractions after the liquid/liquid partition with chloroform. The Folin-Ciocalteu method determined the total phenolic content of the crude extract (CE) and the hydromethanolic fraction (Fraction 1), resulting in a concentration of 0.5853 g/100 g for Fraction 1, and 0.1400 g/100 g for the CE. Taking into account the results of the DPPH, the free radical scavenging capacity was confirmed. The formation of complexes with Fe II ions was evaluated by UV/visible spectrometry; results showed that CE has complexing power similar to the positive control (Gingko biloba extract).The inhibitory capacity of samples against the tyrosinase enzyme was determined by the oxidation of L-DOPA, providing IC50 values of 13.3 μg·mL−1 (CE) and 6.6 μg·mL−1 (Fraction 1). The values indicate that Fraction 1 was more active and showed a higher inhibitory power on the tyrosinase enzyme than the ascorbic acid, used as positive control. The hydromethanolic extract of T. triangulare proved to have powerful antioxidant activity and to inhibit the tyrosinase enzyme; its potential is increased after the partition with chloroform. PMID:26784338
The formation of ammonium cobalt (II) phosphate was utilized to synthesize unprecedented 3D structures of Co3O4, triangular prisms and trunk-like structures, via a self-supported and organics-free method. The length of a triangular side of the prepared 3D triangular prisms is ~1...
Institute of Scientific and Technical Information of China (English)
郑鑫; 解学关; 王安远; 张义鹏; 高伟阳; 蒋良福; 陈星隆; 张国佑; 丁健; 周飞亚; 宋永焕; 李晓阳
2011-01-01
目的 对腕关节三角纤维软骨复合体(TFCC)损伤行关节镜检查,并分析其疗效.方法 对2006年1月至2009年12月诊断为TFCC损伤并行腕关节镜治疗的15例患者进行回顾性分析,其中男6例、女9例,平均年龄42岁,平均随访时间26.5个月.根据Palmer分型,Ⅰ型损伤5例(ⅠA型3例,ⅠB型1例,ⅠD型1例),Ⅱ型损伤10例(ⅡA型6例,ⅡC型4例).所有患者保守治疗3个月以上无效后行关节镜治疗.测量指标:腕关节疼痛、握力、关节活动度、腕关节评分(改良Mayo评分)、DASH问卷.结果 术后15例患者腕关节疼痛均有缓解,握力改善;腕关节屈伸(129±26)°,桡尺偏(40±8)°,旋转(174±11)°.按照改良Mayo评分:优3例,良8例,可4例;优良率为73%.术后DASH评分为4～28分,平均(15±7)分.结论 关节镜对于TFCC损伤的诊断明显优于MRI检查,而且关节镜能在检查的同时进行治疗,应作为腕尺痛的常规诊断手段.关节镜治疗各型TFCC损伤均能缓解疼痛,但Ⅰ型效果好于Ⅱ型.伴有尺骨正变异的TFCC损伤应同时行尺骨缩短术以提高术后效果.%Objective The objective of this study was to determine the efficiency of arthroscopic diagnosis and repair of triangular fibrocartilage complex (TFCC) tears. Methods Fifteen cases of TFCC tears diagnosed and treated with arthroscopic repair in our hospital between January 2006 and December 2009 were retrospectively reviewed. There were six males and nine females. The average age was 42 years. The average follow-up was 26.5 months. TFCC tears were classified by Palmer classification as follows:ⅠA (3 cases),ⅠB (1 case),ⅠD (1 case),ⅡA (6 cases),and ⅡC (4 cases). Arthroscopic repair was performed after at least 3 months of conservative treatment failed. Wrist pain,grip strength,range of motion (ROM),wrist score (modified Mayo wrist score),disabilities of the arm,shoulder,and hand questionnaire (DASH) score were evaluated. Results Postoperatively alleviation of
Directory of Open Access Journals (Sweden)
Miss Maya V.Mawale
2014-08-01
Full Text Available As soil is complex system and soil fertility represents crop productivity and soil productivity hence MIMO system is a necessity of fuzzy logic controller model design using simulation technique. Same model gives prediction of lots of problem and save development time. Modelling and simulation tools made a dynamic evolution in the design and control of prediction system. The basic requirements of prediction system are accuracy in result. The objective of this paper is to investigate the effect of triangular membership functions in the developed Simulink model of Mamdani model based fuzzy control for prediction of soil productivity. The built in membership functions of Matlab is selected for evaluation. The evaluation is done using the developed 207 fuzzy rules through the implementation in Matlab/Simulink model. The results of all soil parameter are analysed. The performances of triangular membership functions on mamdani model based fuzzy control starting currents are concerned for the developed model.
Block-triangular preconditioners for PDE-constrained optimization
Rees, Tyrone
2010-11-26
In this paper we investigate the possibility of using a block-triangular preconditioner for saddle point problems arising in PDE-constrained optimization. In particular, we focus on a conjugate gradient-type method introduced by Bramble and Pasciak that uses self-adjointness of the preconditioned system in a non-standard inner product. We show when the Chebyshev semi-iteration is used as a preconditioner for the relevant matrix blocks involving the finite element mass matrix that the main drawback of the Bramble-Pasciak method-the appropriate scaling of the preconditioners-is easily overcome. We present an eigenvalue analysis for the block-triangular preconditioners that gives convergence bounds in the non-standard inner product and illustrates their competitiveness on a number of computed examples. Copyright © 2010 John Wiley & Sons, Ltd.
(2-1)-Ideal amenability of triangular banach algebras
Indian Academy of Sciences (India)
S Etemad; M Ettefagh
2015-05-01
Let $\\mathcal{A}$ and $\\mathcal{B}$ be two unital Banach algebras and let $\\mathcal{M}$ be an unital Banach $\\mathcal{A}$, $\\mathcal{B}$-module. Also, let $\\mathcal{T}=\\left[\\begin{smallmatrix} \\mathcal{A} & \\mathcal{M}\\\\ & \\mathcal{B}\\end{smallmatrix}\\right]$ be the corresponding triangular Banach algebra. Forrest and Marcoux (Trans. Amer. Math. Soc. 354 (2002) 1435–1452) have studied the -weak amenability of triangular Banach algebras. In this paper, we investigate (2-1)-ideal amenability of $\\mathcal{T}$ for all ≥ 1. We introduce the structure of ideals of these Banach algebras and then, we show that (2-1)-ideal amenability of $\\mathcal{T}$ depends on (2-1)-ideal amenability of Banach algebras $\\mathcal{A}$ and $\\mathcal{B}$.
Seven Means, Generalized Triangular Discrimination, and Generating Divergence Measures
Directory of Open Access Journals (Sweden)
Inder Jeet Taneja
2013-04-01
Full Text Available Jensen-Shannon, J-divergence and Arithmetic-Geometric mean divergences are three classical divergence measures known in the information theory and statistics literature. These three divergence measures bear interesting inequality among the three non-logarithmic measures known as triangular discrimination, Hellingar’s divergence and symmetric chi-square divergence. However, in 2003, Eve studied seven means from a geometrical point of view, which are Harmonic, Geometric, Arithmetic, Heronian, Contra-harmonic, Root-mean square and Centroidal. In this paper, we have obtained new inequalities among non-negative differences arising from these seven means. Correlations with generalized triangular discrimination and some new generating measures with their exponential representations are also presented.
Highly efficient reflective Dammann grating with a triangular structure.
Wang, Jin; Zhou, Changhe; Ma, Jianyong; Zong, Yonghong; Jia, Wei
2016-07-01
A highly efficient reflective Dammann grating with a triangular structure operating at 1064 nm wavelength under normal incidence for TE polarization is designed and fabricated. Rigorous coupled wave analysis and particle swarm optimization algorithms are adopted to design and analyze the properties. The triangular reflective grating could cancel the 0th order, and the mechanism is clarified by the simplified modal method. The gratings are fabricated by direct laser writing lithography. The diffraction efficiency of fabricated grating is more than 86% at 1064 nm wavelength (97.6% in theory). This reflective grating should be a useful optical element in the field of high-power lasers as well as other reflective applications. PMID:27409211
A Novel Triangular Shaped UWB Fractal Antenna Using Circular Slot
Shahu, Babu Lal; Pal, Srikanta; Chattoraj, Neela
2016-03-01
The article presents the design of triangular shaped fractal based antenna with circular slot for ultra wideband (UWB) application. The antenna is fed using microstrip line and has overall dimension of 24×24×1.6 mm3. The proposed antenna is covering the wide frequency bandwidth of 2.99-11.16 GHz and is achieved using simple fractal based triangular-circular geometries and asymmetrical ground plane. The antenna is designed and parametrical studies are performed using method of moment (MOM) based Full Wave Electromagnetic (EM) software Simulator Zeland IE3D. The prototype of proposed antenna is fabricated and tested to compare the simulated and measured results of various antenna parameters. The antenna has good impedance bandwidth, nearly constant gain and stable radiation pattern. Measured return loss shows fair agreement with simulated one. Also measured group delay variation obtained is less than 1.0 ns, which proves good time domain behavior of the proposed antenna.
Many body localization in two dimensional square and triangular lattices
Gonzalez-Garcia, L; Paredes, R
2016-01-01
Ultracold interacting Bose atoms placed in disordered two dimensional optical lattices with square and triangular symmetries are found to be localized above a certain disorder strength amplitude. From a Gross-Pitaevskii mean analysis we determine the localization length as a function of the disorder strength and investigate the energy spectrum in terms of the disorder magnitude. We found that the localization length is observed to decrease faster in triangular geometries than in square ones. In the presence of a harmonic confinement localization is observed at the center of the trap. The analysis of the energy spectrum reveals that discrete energy levels acquire a finite width that is always smaller than the distance among energy levels.
On the Construction of Jointly Superregular Lower Triangular Toeplitz Matrices
DEFF Research Database (Denmark)
Hansen, Jonas; Østergaard, Jan; Kudahl, Johnny;
2016-01-01
Superregular matrices have the property that all of their submatrices, which can be full rank are so. Lower triangular superregular matrices are useful for e.g., maximum distance separable convolutional codes as well as for (sequential) network codes. In this work, we provide an explicit design...... for all superregular lower triangular Toeplitz matrices in GF(2p) for the case of matrices with dimensions less than or equal to 5 × 5. For higher dimensional matrices, we present a greedy algorithm that find a solution provided the field size is sufficiently high. We also introduce the notions of jointly...... superregular and product preserving jointly superregular matrices, and extend our explicit constructions of superregular matrices to these cases. Jointly superregular matrices are necessary to achieve optimal decoding capabilities for the case of codes with a rate lower than 1/2, and the product preserving...
Energy Technology Data Exchange (ETDEWEB)
Ranmohotti, K.G. Sanjaya; Montasserasadi, M. Dariush; Choi, Jonglak; Yao, Yuan; Mohanty, Debasish; Josepha, Elisha A.; Adireddy, Shiva; Caruntu, Gabriel [Department of Chemistry and the Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148-2820 (United States); Wiley, John B., E-mail: jwiley@uno.edu [Department of Chemistry and the Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148-2820 (United States)
2012-06-15
Highlights: ► Topochemical reactions involving intercalation allow construction of metal chalcogenide arrays within perovskite hosts. ► Gaseous chalcogen hydrides serve as effect reactants for intercalation of sulfur and selenium. ► New compounds prepared by a two-step intercalation strategy are presented. -- Abstract: A two-step topochemical reaction strategy utilizing oxidative intercalation with gaseous chalcogen hydrides is presented. Initially, the Dion-Jacobson-type layered perovskite, RbLaNb{sub 2}O{sub 7}, is intercalated reductively with rubidium metal to make the Ruddlesden-Popper-type layered perovskite, Rb{sub 2}LaNb{sub 2}O{sub 7}. This compound is then reacted at room-temperature with in situ generated H{sub 2}S gas to create Rb-S layers within the perovskite host. Rietveld refinement of X-ray powder diffraction data (tetragonal, a = 3.8998(2) Å, c = 15.256(1) Å; space group P4/mmm) shows the compound to be isostructural with (Rb{sub 2}Cl)LaNb{sub 2}O{sub 7} where the sulfide resides on a cubic interlayer site surrounded by rubidium ions. The mass increase seen on sulfur intercalation and the refined S site occupation factor (∼0.8) of the product indicate a higher sulfur content than expected for S{sup 2−} alone. This combined with the Raman studies, which show evidence for an H-S stretch, indicate that a significant fraction of the intercalated sulfide exists as hydrogen sulfide ion. Intercalation reactions with H{sub 2}Se{sub (g)} were also carried out and appear to produce an isostructural selenide compound. The utilization of such gaseous hydride reagents could significantly expand multistep topochemistry to a larger number of intercalants.
Mott Insulating Ground State on a Triangular Surface Lattice
International Nuclear Information System (INIS)
Momentum-resolved direct and inverse photoemission spectra of the K/Si(111)-(√(3)x√(3))R30 degree-B interface reveals the presence of strongly localized surface states. The K overlayer remains nonmetallic up to the saturation coverage. This system most likely presents the first experimental realization of a frustrated spin 1/2 Heisenberg antiferromagnet on a two-dimensional triangular lattice. copyright 1997 The American Physical Society
Seven Means, Generalized Triangular Discrimination, and Generating Divergence Measures
Inder Jeet Taneja
2013-01-01
Jensen-Shannon, J-divergence and Arithmetic-Geometric mean divergences are three classical divergence measures known in the information theory and statistics literature. These three divergence measures bear interesting inequality among the three non-logarithmic measures known as triangular discrimination, Hellingar’s divergence and symmetric chi-square divergence. However, in 2003, Eve studied seven means from a geometrical point of view, which are Harmonic, Geometric, Arithmetic, Heronian, C...
A novel optical multilayer hydrophone with a triangular pyramid substrate
Institute of Scientific and Technical Information of China (English)
Suyong Wu; Xingwu Long; Kaiyong Yang; Yun Huang
2011-01-01
@@ A novel concept for an optical multilayer ultrasonic hydrophone with the sensing film deposited on a triangular pyramid glass substrate is proposed. Using the calculation model for the spectral coefficients' derivatives of a dielectric multilayer optical coating, the acousto-optic sensitivity characteristic of the hydrophone is analyzed with different measurement laser polarizations and incident angles. We present a reasonable method and adjusting strategy for the optimum working point selection of the ultrasound measurement. Analytic results show that the novel hydrophone possesses all the other merits of a plate glass substrate optical multilayer hydrophone but with improved detection sensitivity. A longer measurement time without distortion decreases the difficulty of high frequency signal circuits. Spatial split of the ultrasound signal caused by the substrate's triangular pyramid roof simplifies the spatial spot area correction,which contributes to the accurate calibration of the hydrophone's wideband frequency response.%A novel concept for an optical multilayer ultrasonic hydrophone with the sensing film deposited on a triangular pyramid glass substrate is proposed. Using the calculation model for the spectral coefficients'derivatives of a dielectric multilayer optical coating, the acousto-optic sensitivity characteristic of the hydrophone is analyzed with different measurement laser polarizations and incident angles. We present a reasonable method and adjusting strategy for the optimum working point selection of the ultrasound measurement. Analytic results show that the novel hydrophone possesses all the other merits of a plate glass substrate optical multilayer hydrophone but with improved detection sensitivity. A longer measurement time without distortion decreases the difficulty of high frequency signal circuits. Spatial split of the ultrasound signal caused by the substrate's triangular pyramid roof simplifies the spatial spot area correction
RNA folding on the 3D triangular lattice
Directory of Open Access Journals (Sweden)
Mayne Martin
2009-11-01
Full Text Available Abstract Background Difficult problems in structural bioinformatics are often studied in simple exact models to gain insights and to derive general principles. Protein folding, for example, has long been studied in the lattice model. Recently, researchers have also begun to apply the lattice model to the study of RNA folding. Results We present a novel method for predicting RNA secondary structures with pseudoknots: first simulate the folding dynamics of the RNA sequence on the 3D triangular lattice, next extract and select a set of disjoint base pairs from the best lattice conformation found by the folding simulation. Experiments on sequences from PseudoBase show that our prediction method outperforms the HotKnot algorithm of Ren, Rastegari, Condon and Hoos, a leading method for RNA pseudoknot prediction. Our method for RNA secondary structure prediction can be adapted into an efficient reconstruction method that, given an RNA sequence and an associated secondary structure, finds a conformation of the sequence on the 3D triangular lattice that realizes the base pairs in the secondary structure. We implemented a suite of computer programs for the simulation and visualization of RNA folding on the 3D triangular lattice. These programs come with detailed documentation and are accessible from the companion website of this paper at http://www.cs.usu.edu/~mjiang/rna/DeltaIS/. Conclusion Folding simulation on the 3D triangular lattice is effective method for RNA secondary structure prediction and lattice conformation reconstruction. The visualization software for the lattice conformations of RNA structures is a valuable tool for the study of RNA folding and is a great pedagogic device.
Maxima of Dirichlet and triangular arrays of gamma variables
Bose, Arup; Dasgupta, Amites; Maulik, Krishanu
2008-01-01
Consider a rowwise independent triangular array of gamma random variables with varying parameters. Under several different conditions on the shape parameter, we show that the sequence of row-maximums converges weakly after linear or power transformation. Depending on the parameter combinations, we obtain both Gumbel and non-Gumbel limits. The weak limits for maximum of the coordinates of certain Dirichlet vectors of increasing dimension are also obtained using the gamma representation.
NEW SECOND ORDER NONCONFORMING TRIANGULAR ELEMENT FOR PLANAR ELASTICITY PROBLEMS
Institute of Scientific and Technical Information of China (English)
Chen Shaochun; Zheng Yanjun; Mao Shipeng
2011-01-01
In the use of finite element methods to the planar elasticity problems, one difficulty is to overcome locking when elasticity constant λ→∞. In the case of traction boundary condition, another difficulty is to make the discrete Korn's second inequality valid. In this paper, a triangular element is presented. We prove that this element is locking-free, the discrete Korn's second inequality holds and the convergence order is two.
Procrustes Problems for General, Triangular, and Symmetric Toeplitz Matrices
Directory of Open Access Journals (Sweden)
Juan Yang
2013-01-01
Full Text Available The Toeplitz Procrustes problems are the least squares problems for the matrix equation AX=B over some Toeplitz matrix sets. In this paper the necessary and sufficient conditions are obtained about the existence and uniqueness for the solutions of the Toeplitz Procrustes problems when the unknown matrices are constrained to the general, the triangular, and the symmetric Toeplitz matrices, respectively. The algorithms are designed and the numerical examples show that these algorithms are feasible.
Effective Lateral Canthal Lengthening with Triangular Rotation Flap
2016-01-01
In Korea, lateral canthoplasty, along with medial epicanthoplasty, has become popular over the past years to widen the horizontal length of the palpebral fissure. However, the effect of the surgery differs greatly depending on the shape and structure of the eyes. If over-widened, complications such as eversion, scarring, and conjunctival exposure may occur. Thus, the author of this study suggests a more effective and safe method for lateral canthal lengthening that causes minimal complications. A total of 236 patients underwent lateral canthoplasty between July 2007 and December 2015. For each patient, a triangular flap 4–5 mm away from the lateral canthus was elevated and rotated 45 degrees laterally while the continuity of the lower eyelid gray line was maintained. A new lateral canthus was created by fixating the rotation flap to the lateral orbital rim with minimal skin trimming and tension-free sutures, preventing relapse and maintaining a triangular shape. In more than 95% of cases, effective and satisfactory extension was achieved. On average, a 3 mm extension of the lateral canthus was achieved. There were minor complications such as wound dehiscence, webbing, and scarring, which were easily corrected. The author not only extended the lateral canthus 3–4 mm laterally but also maintained the continuity of the gray line on the lower lid as a more natural-looking triangular shape, while minimizing complications such as webbing and conjunctival exposure.
Parabolic similariton Yb-fiber laser with triangular pulse evolution
Wang, Sijia; Wang, Lei
2016-04-01
We propose a novel mode-locked fiber laser design which features a passive nonlinear triangular pulse formation and self-similar parabolic pulse amplification intra cavity. Attribute to the nonlinear reshaping progress in the passive fiber, a triangular-profiled pulse with negative-chirp is generated and paved the way for rapid and efficient self-similar parabolic evolution in a following short-length high-gain fiber. In the meanwhile, the accompanied significantly compressed narrow spectrum from this passive nonlinear reshaping also gives the promise of pulse stabilization and gain-shaping robustness without strong filtering. The resulting short average intra-cavity pulse duration, low amplified spontaneous emission (ASE) and low intra-cavity power loss are essential for the low-noise operation. Simulations predict this modelocked fiber laser allows for high-energy ultra-short transform-limited pulse generation exceeding the gain bandwidth. The output pulse has a de-chirped duration (full-width at half maximum, FWHM) of 27 fs. In addition to the ultrafast laser applications, the proposed fiber laser scheme can support low-noise parabolic and triangular pulse trains at the same time, which are also attractive in optical pulse shaping, all-optical signal processing and high-speed communication applications.
Magnetic properties of a spin-1 triangular Ising system
International Nuclear Information System (INIS)
We studied some magnetic behaviors of the Blume-Capel (BC) model in a site diluted triangular lattice by means of the effective-field theory (EFT) with correlations. The effects of the exchange interaction (J), crystal field (D), concentration (p) and temperature (T) on the magnetic properties of the spin-1 BC model in a triangular lattice, such as magnetization, susceptibility, phase diagram and hysteresis behaviors, are investigated in detail. The phase diagrams of the system are presented in two different planes. The tricritical point as well as the tetracritical and critical end special points are found to depend on the physical parameters of the system. Moreover, when the hysteresis behaviors of the system are examined, single and double hysteresis loops are observed for various values of the physical parameters. We show that the hysteresis loops have different coercive field points in which the susceptibility makes a peak at these points. - Highlights: • The triangular Ising system is investigated within EFT with correlations. • The effects of the interaction parameters on spin-1 BC model are studied. • The phase diagrams are found for the different interaction parameters. • The hysteresis behaviors of the system are examined. • The system shows the tricritical, tetracritical and critical end special points
Magnetic properties of a spin-1 triangular Ising system
Energy Technology Data Exchange (ETDEWEB)
Ertaş, Mehmet [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Kocakaplan, Yusuf [Graduate School of Natural and Applied Sciences, Erciyes University, 38039 Kayseri (Turkey); Kantar, Ersin, E-mail: ersinkantar@erciyes.edu.tr [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)
2015-07-15
We studied some magnetic behaviors of the Blume-Capel (BC) model in a site diluted triangular lattice by means of the effective-field theory (EFT) with correlations. The effects of the exchange interaction (J), crystal field (D), concentration (p) and temperature (T) on the magnetic properties of the spin-1 BC model in a triangular lattice, such as magnetization, susceptibility, phase diagram and hysteresis behaviors, are investigated in detail. The phase diagrams of the system are presented in two different planes. The tricritical point as well as the tetracritical and critical end special points are found to depend on the physical parameters of the system. Moreover, when the hysteresis behaviors of the system are examined, single and double hysteresis loops are observed for various values of the physical parameters. We show that the hysteresis loops have different coercive field points in which the susceptibility makes a peak at these points. - Highlights: • The triangular Ising system is investigated within EFT with correlations. • The effects of the interaction parameters on spin-1 BC model are studied. • The phase diagrams are found for the different interaction parameters. • The hysteresis behaviors of the system are examined. • The system shows the tricritical, tetracritical and critical end special points.
Energy Technology Data Exchange (ETDEWEB)
Hayat, Nasir; Ahmad, Mushtaq, E-mail: nasirhayat@uet.edu.pk [Faculty of Mechanical Engineering, UET, Lahore (Pakistan)
2016-01-15
This study investigates the effects of computed tomography (CT) parameters on the quality and size of the reverse triangular surface model with an objective of obtaining an accurate 3D triangular surface model of complex-shaped customized objects for reverse engineering and many other applications such as surgical planning and finite element analysis. For this purpose, the fibula of a human knee joint was CT scanned by changing various parameters (slice thickness, slice spacing, pixel size, X-ray tube current and helical pitch) over wide ranges. Three-dimensional triangular surface models were created from point cloud data extracted from the CT image data. To assess the influences of scanning parameters on the surface quality and accuracy, the resulting surface models were qualitatively compared based on various anatomical features. Statistical analysis was used to quantify the deviations of surface models with different scanning parameter levels from the reference CT surface model. The results show that these parameters to a varying degree affect the surface quality, reproduction of various anatomical details and size of the resulting surface model. Moreover, these parameters are highly dependent on each other. Interactive effects of these parameters have been discussed and recommendations have been made for parameter settings. The results of the study would help to improve the accuracy of the 3D surface models required for customized implants and other applications. (author)
International Nuclear Information System (INIS)
This study investigates the effects of computed tomography (CT) parameters on the quality and size of the reverse triangular surface model with an objective of obtaining an accurate 3D triangular surface model of complex-shaped customized objects for reverse engineering and many other applications such as surgical planning and finite element analysis. For this purpose, the fibula of a human knee joint was CT scanned by changing various parameters (slice thickness, slice spacing, pixel size, X-ray tube current and helical pitch) over wide ranges. Three-dimensional triangular surface models were created from point cloud data extracted from the CT image data. To assess the influences of scanning parameters on the surface quality and accuracy, the resulting surface models were qualitatively compared based on various anatomical features. Statistical analysis was used to quantify the deviations of surface models with different scanning parameter levels from the reference CT surface model. The results show that these parameters to a varying degree affect the surface quality, reproduction of various anatomical details and size of the resulting surface model. Moreover, these parameters are highly dependent on each other. Interactive effects of these parameters have been discussed and recommendations have been made for parameter settings. The results of the study would help to improve the accuracy of the 3D surface models required for customized implants and other applications. (author)
Directory of Open Access Journals (Sweden)
Yanbing Ju
2014-01-01
Full Text Available This paper studies the multiattribute decision making (MADM problems in which the attribute values take the form of dual hesitant fuzzy triangular linguistic elements and the weights of attributes take the form of real numbers. Firstly, to solve the situation where the membership degree and the nonmembership degree of an element to a triangular linguistic variable, the concept, operational laws, score function, and accuracy function of dual hesitant fuzzy triangular linguistic elements (DHFTLEs are defined. Then, some dual hesitant fuzzy triangular linguistic geometric aggregation operators are developed for aggregating the DHFTLEs, including dual hesitant fuzzy triangular linguistic weighted geometric (DHFTLWG operator, dual hesitant fuzzy triangular linguistic ordered weighted geometric (DHFTLOWG operator, dual hesitant fuzzy triangular linguistic hybrid geometric (DHFTLHG operator, generalized dual hesitant fuzzy triangular linguistic weighted geometric (GDHFTLWG operator, and generalized dual hesitant fuzzy triangular linguistic ordered weighted geometric (GDHFTLOWG operator. Furthermore, some desirable properties of these operators are investigated in detail. Based on the proposed operators, an approach to MADM with dual hesitant fuzzy triangular linguistic information is proposed. Finally, a numerical example for investment alternative selection is given to illustrate the application of the proposed method.
Dung Y. Liao; Yu C. Chai; Sue H. Wang; Chih W. Chen; Ming S. Tsai
2015-01-01
In this study, leaves and stems of Talinum triangulare were sequentially extracted with phosphate buffer solution to obtain PTL and PTS (phosphate buffered extracts of T. triangulare leaves and stems), with 75% ethanol to obtained ETL and ETS (ethanol extracts of T. triangulare leaves and stems), or with 90°C boiling water to obtain WTL and WTS (water extracts of T. triangulare leaves and stems). We investigated the antioxidant activities of various T. triangulare extracts, analyzed the extra...
Institute of Scientific and Technical Information of China (English)
Sutthisak Phongthanapanich; Pramote Dechaumphai
2011-01-01
Level set methods are widely used for predicting evolutions of complex free surface topologies,such as the crystal and crack growth,bubbles and droplets deformation,spilling and breaking waves,and two-phase flow phenomena.This paper presents a characteristic level set equation which is derived from the two-dimensional level set equation by using the characteristic-based scheme.An explicit finite volume element method is developed to discretize the equation on triangular grids.Several examples are presented to demonstrate the performance of the proposed method for calculating interface evolutions in time.The proposed level set method is also coupled with the Navier-Stokes equations for two-phase immiscible incompressible flow analysis with surface tension.The Rayleigh-Taylor instability problem is used to test and evaluate the effectiveness of the proposed scheme.
Gershenson, Carlos
2011-01-01
The term complexity derives etymologically from the Latin plexus, which means interwoven. Intuitively, this implies that something complex is composed by elements that are difficult to separate. This difficulty arises from the relevant interactions that take place between components. This lack of separability is at odds with the classical scientific method - which has been used since the times of Galileo, Newton, Descartes, and Laplace - and has also influenced philosophy and engineering. In recent decades, the scientific study of complexity and complex systems has proposed a paradigm shift in science and philosophy, proposing novel methods that take into account relevant interactions.
Improved triangular prism methods for fractal analysis of remotely sensed images
Zhou, Yu; Fung, Tung; Leung, Yee
2016-05-01
Feature extraction has been a major area of research in remote sensing, and fractal feature is a natural characterization of complex objects across scales. Extending on the modified triangular prism (MTP) method, we systematically discuss three factors closely related to the estimation of fractal dimensions of remotely sensed images. They are namely the (F1) number of steps, (F2) step size, and (F3) estimation accuracy of the facets' areas of the triangular prisms. Differing from the existing improved algorithms that separately consider these factors, we simultaneously take all factors to construct three new algorithms, namely the modification of the eight-pixel algorithm, the four corner and the moving-average MTP. Numerical experiments based on 4000 generated images show their superior performances over existing algorithms: our algorithms not only overcome the limitation of image size suffered by existing algorithms but also obtain similar average fractal dimension with smaller standard deviation, only 50% for images with high fractal dimensions. In the case of real-life application, our algorithms more likely obtain fractal dimensions within the theoretical range. Thus, the fractal nature uncovered by our algorithms is more reasonable in quantifying the complexity of remotely sensed images. Despite the similar performance of these three new algorithms, the moving-average MTP can mitigate the sensitivity of the MTP to noise and extreme values. Based on the numerical and real-life case study, we check the effect of the three factors, (F1)-(F3), and demonstrate that these three factors can be simultaneously considered for improving the performance of the MTP method.
Collision geometry fluctuations and triangular flow in heavy-ion collisions
Alver, B
2010-01-01
We introduce the concepts of participant triangularity and triangular flow in heavy-ion collisions, analogous to the definitions of participant eccentricity and elliptic flow. The participant triangularity characterizes the triangular anisotropy of the initial nuclear overlap geometry and arises from event-by-event fluctuations in the participant-nucleon collision points. In studies using a multi-phase transport model (AMPT), a triangular flow signal is observed that is proportional to the participant triangularity and corresponds to a large third Fourier coefficient in two-particle azimuthal correlation functions. Using two-particle azimuthal correlations at large pseudorapidity separations measured by the PHOBOS and STAR experiments, we show that this Fourier component is also present in data. Ratios of the second and third Fourier coefficients in data exhibit similar trends as a function of centrality and transverse momentum as in AMPT calculations. These findings suggest a significant contribution of tria...
A Short Polarization Converter Using a Triangular Waveguide
Yamauchi, Junji; Yamanoue, Masahiro; Nakano, Hisamatsu
2008-01-01
A novel polarization converter using a triangular waveguide is proposed and analyzed by the imaginary-distance beam-propagation method based on Yee's mesh and the finite-difference time-domain method. The polarization conversion length is investigated as a function of relative refractive index difference. It is found, for a silicon core embedded in a silica cladding, that the conversion length is 2 mum, while the insertion loss is 0.5 dB at a wavelength of 1.55 mum. The extinction ratio is mo...
THE EFFECT OF AN ELASTIC TRIANGULAR INCLUSION ON A CRACK
Institute of Scientific and Technical Information of China (English)
焦贵德; 王银邦
2003-01-01
The interaction between an elastic triangular inclusion and a crack is investigated. The problem is formulated using the boundary integral equations for traction boundary value problems derived by Chau and Wang as basic equations. By using the continuity condition of traction and displacement on interface as supplement equations, a set of equations for solving the interaction problem between an inclusion and a crack are obtained, which are solved by asing a new boundary element method. The results in terms of stress intensity factors (SIFs) are calculated for a variety of crack-inclusion arrangements and the elastic constants of the matrix and the inclusion. The results are valuable for studying new composite materials.
A flat triangular shell element with Loof nodes
DEFF Research Database (Denmark)
Poulsen, Peter Noe; Damkilde, Lars
1996-01-01
In the formulation of flat shell elements it is difficult to achieve inter-element compatibility between membrane and transverse displacements for non-coplanar elements. Many elements lack proper nodal degrees of freedom to model intersections making the assembly of elements troublesome. A flat...... triangular shell element is established by a combination of a new plate bending element DKTL and the well-known linear membrane strain element LST, and for this element the above-mentioned deficiences are avoided. The plate bending element DKTL is based on Discrete Kirchhoff Theory and Loof nodes. The nodal...
CLOSED SMOOTH SURFACE DEFINED FROM CUBIC TRIANGULAR SPLINES
Institute of Scientific and Technical Information of China (English)
Ren-zhong Feng; Ren-hong Wang
2005-01-01
In order to construct closed surfaces with continuous unit normal, we introduce a new spline space on an arbitrary closed mesh of three-sided faces. Our approach generalizes an idea of Goodman and is based on the concept of 'Geometric continuity' for piecewise polynomial parametrizations. The functions in the spline space restricted to the faces are cubic triangular polynomials. A basis of the spline space is constructed of positive functions which sum to 1. It is also shown that the space is suitable for interpolating data at the midpoints of the faces.
Triangular Dynamic Architecture for Distributed Computing in a LAN Environment
Hossain, M Shahriar; Fuad, M Muztaba; Deb, Debzani
2011-01-01
A computationally intensive large job, granulized to concurrent pieces and operating in a dynamic environment should reduce the total processing time. However, distributing jobs across a networked environment is a tedious and difficult task. Job distribution in a Local Area Network based on Triangular Dynamic Architecture (TDA) is a mechanism that establishes a dynamic environment for job distribution, load balancing and distributed processing with minimum interaction from the user. This paper introduces TDA and discusses its architecture and shows the benefits gained by utilizing such architecture in a distributed computing environment.
Multiple Discrete Endogenous Variables in Weakly-Separable Triangular Models
Directory of Open Access Journals (Sweden)
Sung Jae Jun
2016-02-01
Full Text Available We consider a model in which an outcome depends on two discrete treatment variables, where one treatment is given before the other. We formulate a three-equation triangular system with weak separability conditions. Without assuming assignment is random, we establish the identification of an average structural function using two-step matching. We also consider decomposing the effect of the first treatment into direct and indirect effects, which are shown to be identified by the proposed methodology. We allow for both of the treatment variables to be non-binary and do not appeal to an identification-at-infinity argument.
Triangular preconditioners for saddle point problems with a penalty term
Energy Technology Data Exchange (ETDEWEB)
Klawonn, A. [Westfaelische Wilhelms-Universitaet, Muenster (Germany)
1996-12-31
Triangular preconditioners for a class of saddle point problems with a penalty term are considered. An important example is the mixed formulation of the pure displacement problem in linear elasticity. It is shown that the spectrum of the preconditioned system is contained in a real, positive interval, and that the interval bounds can be made independent of the discretization and penalty parameters. This fact is used to construct bounds of the convergence rate of the GMRES method used with an energy norm. Numerical results are given for GMRES and BI-CGSTAB.
Mott transition and magnetism on the anisotropic triangular lattice
Acheche, S.; Reymbaut, A.; Charlebois, M.; Sénéchal, D.; Tremblay, A.-M.S.
2016-01-01
Spin-liquid behavior was recently suggested experimentally in the moderately one-dimensional organic compound $\\kappa$-H$_3$(Cat-EDT-TTF)$_2$. This compound can be modeled by the one-band Hubbard model on the anisotropic triangular lattice with $t^\\prime/t \\simeq 1.5$, where $t'$ is the minority hopping. It thus becomes important to extend previous studies, that were performed in the range $0 \\leq t'/t \\leq 1.2$, to find out whether there is a regime where Mott insulating behavior can be foun...
Algorithms for Computing Triangular Decompositions of Polynomial Systems
Chen, Changbo
2011-01-01
We propose new algorithms for computing triangular decompositions of polynomial systems incrementally. With respect to previous works, our improvements are based on a {\\em weakened} notion of a polynomial GCD modulo a regular chain, which permits to greatly simplify and optimize the sub-algorithms. Extracting common work from similar expensive computations is also a key feature of our algorithms. In our experimental results the implementation of our new algorithms, realized with the {\\RegularChains} library in {\\Maple}, outperforms solvers with similar specifications by several orders of magnitude on sufficiently difficult problems.
Apex-angle-dependent resonances in triangular split ring resonators
Burnett, Max A
2016-01-01
Along with other frequency selective structures [1] (circles and squares), triangular split-ring resonators (TSRRs) only allow frequencies near the center resonant frequency to propagate. Further, TSRRs are attractive due to their small surface area [2], comparatively, and large quality factors (Q) factors as previously investigated by Gay-Balmaz, et al. [3]. In this work we examine the effects of varying the apex angle on the resonant frequency, the Q factor, and the phase shift imparted by the TSRR element within the GHz frequency regime.
Triangular and Trapezoidal Fuzzy State Estimation with Uncertainty on Measurements
Directory of Open Access Journals (Sweden)
Mohammad Sadeghi Sarcheshmah
2012-01-01
Full Text Available In this paper, a new method for uncertainty analysis in fuzzy state estimation is proposed. The uncertainty is expressed in measurements. Uncertainties in measurements are modelled with different fuzzy membership functions (triangular and trapezoidal. To find the fuzzy distribution of any state variable, the problem is formulated as a constrained linear programming (LP optimization. The viability of the proposed method would be verified with the ones obtained from the weighted least squares (WLS and the fuzzy state estimation (FSE in the 6-bus system and in the IEEE-14 and 30 bus system.
STL Triangular Mesh Generation Based on SAT Model
Directory of Open Access Journals (Sweden)
Yuwei Zhang
2013-06-01
Full Text Available Mesh generation is a fundamental technique in multiple domains. In this study, a STL triangular mesh generation method based on SAT model is proposed. Two novel triangulation methods, the constrained Delaunay algorithm and the grid subtraction algorithm, are employed on the multi-loop planer regions and the curved surfaces respectively. For the use of node adjustment, the mesh nodes on the surface boundary are strictly matched, with no cracks created on the joint of model surfaces. Experiments show that the proposed solution works effectively and high quality of the mesh model is achieved.
Triangular-slot monopole antenna for on-body communications
Martín Cantero, Alejandro
2014-01-01
ABSTRACT: The objective of this project is to optimize and redesign a Triangular monopole slot antenna designed to work in On-Body communications. Originally, the antenna was working in the 5.8 GHz ISM band and in the first steps of the design we had to modify the antenna to establish its resonant frequency in the 2.4 GHz band. Finally, we changed the antenna substrate to CuClad 217LX, since this substrate is more flexible and therefore more optimum for communications on the human body. Durin...
Synthesis and Photocatalytic Activity of Ag3PO4 Triangular Prism
Pengyu Dong; Yan Hao; Peiyang Gao; Entian Cui; Qinfang Zhang
2015-01-01
Ag3PO4 triangular prism was synthesized by a facile chemical precipitation approach by simply adjusting external ultrasonic condition. The as-synthesized Ag3PO4 triangular prism was characterized by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectra, and ultraviolet-visible diffuse reflectance (UV-vis DRS) absorption spectra. The photocatalytic activity of Ag3PO4 triangular prism was evaluated by photodegradation of or...
Triangular Differential Quadrature for Bending Analysis of Reissner Plates with Curved Boundaries
Institute of Scientific and Technical Information of China (English)
华永霞; 钟宏志
2003-01-01
The recently proposed concept of the triangular differential quadrature method (TDQM) is applied to the bending analysis of Reissner plates with various curvilinear geometries subjected to various combinations of boundary conditions. A unit isosceles right triangle is used as the standard triangle for all the derivatives expressed using the triangular differential quadrature rule. Geometric transformations are introduced using basis functions to determine the weighting coefficients for the triangular differential quadrature to map an arbitrary curvilinear triangle into the standard triangle. The triangular differential quadrature method provides good accuracy and rapid convergence relative to other available exact and numerical results.
On the interference rejection capabilities of triangular antenna array for cellular base stations
Atat, Rachad
2012-03-01
In this paper, we present the performance analysis of the triangular antenna arrays in terms of the interference rejection capability. In this context, we derive an expression to calculate the spatial interference suppression coefficient for the triangular antenna array with variable number of antenna elements. The performance of the triangular antenna array has been compared with the circular antenna array with respect to interference suppression performance, steering beam pattern, beamwidth and directivity. Simulation results show that the triangular array with large number of elements produces a sharper beamwidth and better interference suppression performance than the circular antenna array. © 2012 IEEE.
Automatic Shape Control of Triangular B-Splines of Arbitrary Topology
Institute of Scientific and Technical Information of China (English)
Ying He; Xian-Feng Gu; Hong Qin
2006-01-01
Triangular B-splines are powerful and flexible in modeling a broader class of geometric objects defined over arbitrary, non-rectangular domains. Despite their great potential and advantages in theory, practical techniques and computational tools with triangular B-splines are less-developed. This is mainly because users have to handle a large number of irregularly distributed control points over arbitrary triangulation. In this paper, an automatic and efficient method is proposed to generate visually pleasing, high-quality triangular B-splines of arbitrary topology. The experimental results on several real datasets show that triangular B-splines are powerful and effective in both theory and practice.
Triangular nanobeam photonic cavities in single crystal diamond
Bayn, Igal; Salzman, Joseph; Kalish, Rafi
2011-01-01
Diamond photonics provides an attractive architecture to explore room temperature cavity quantum electrodynamics and to realize scalable multi-qubit computing. Here we review the present state of diamond photonic technology. The design, fabrication and characterization of a novel triangular cross section nanobeam cavity produced in a single crystal diamond is demonstrated. The present cavity design, based on a triangular cross section allows vertical confinement and better signal collection efficiency than that of slab-based nanocavities, and eliminates the need for a pre-existing membrane. The nanobeam is fabricated by Focused-Ion-Beam (FIB) patterning. The cavity is characterized by a confocal photoluminescence. The modes display quality factors of Q ~220 and are deviated in wavelength by only ~1.7nm from the NV- color center zero phonon line (ZPL). The measured results are found in good agreement with 3D Finite-Difference-Time-Domain (FDTD) calculations. A more advanced cavity design with Q=22,000 is model...
Triangular nanobeam photonic cavities in single-crystal diamond
International Nuclear Information System (INIS)
Diamond photonics provides an attractive architecture to explore room temperature cavity quantum electrodynamics and to realize scalable multi-qubit computing. Here, we review the present state of diamond photonic technology. The design, fabrication and characterization of a novel nanobeam cavity produced in a single crystal diamond are demonstrated. The present cavity design, based on a triangular cross-section, allows vertical confinement and better signal collection efficiency than that of slab-based nanocavities and eliminates the need for a pre-existing membrane. The nanobeam is fabricated by focused-ion-beam (FIB) patterning. The cavity is characterized by confocal photoluminescence. The modes display quality factors of Q∼220 and deviate in wavelength by only ∼1.7 nm from the nitrogen-vacancy (NV-) color center zero phonon line (ZPL). The measured results are found to be in good agreement with three-dimensional finite-difference-time-domain (FDTD) calculations. A more advanced cavity design with Q=22 000 is modeled, showing the potential for high-Q implementations using the triangular geometry. The prospects of this concept and its application in spin non-demolition measurement and quantum computing are discussed.
Triangular Black Phosphorus Atomic Layers by Liquid Exfoliation
Seo, Soonjoo; Lee, Hyun Uk; Lee, Soon Chang; Kim, Yooseok; Kim, Hyeran; Bang, Junhyeok; Won, Jonghan; Kim, Youngjun; Park, Byoungnam; Lee, Jouhahn
2016-03-01
Few-layer black phosphorus (BP) is the most promising material among the two-dimensional materials due to its layered structure and the excellent semiconductor properties. Currently, thin BP atomic layers are obtained mostly by mechanical exfoliation of bulk BP, which limits applications in thin-film based electronics due to a scaling process. Here we report highly crystalline few-layer black phosphorus thin films produced by liquid exfoliation. We demonstrate that the liquid-exfoliated BP forms a triangular crystalline structure on SiO2/Si (001) and amorphous carbon. The highly crystalline BP layers are faceted with a preferred orientation of the (010) plane on the sharp edge, which is an energetically most favorable facet according to the density functional theory calculations. Our results can be useful in understanding the triangular BP structure for large-area applications in electronic devices using two-dimensional materials. The sensitivity and selectivity of liquid-exfoliated BP to gas vapor demonstrate great potential for practical applications as sensors.
Corrosion processes of triangular silver nanoparticles compared to bulk silver
Energy Technology Data Exchange (ETDEWEB)
Keast, V. J., E-mail: vicki.keast@newcastle.edu.au; Myles, T. A. [University of Newcastle, School of Mathematical and Physical Sciences (Australia); Shahcheraghi, N.; Cortie, M. B. [University of Technology Sydney, Institute for Nanoscale Technology (Australia)
2016-02-15
Excessive corrosion of silver nanoparticles is a significant impediment to their use in a variety of potential applications in the biosensing, plasmonic and antimicrobial fields. Here we examine the environmental degradation of triangular silver nanoparticles (AgNP) in laboratory air. In the early stages of corrosion, transmission electron microscopy shows that dissolution of the single-crystal, triangular, AgNP (side lengths 50–120 nm) is observed with the accompanying formation of smaller, polycrystalline Ag particles nearby. The new particles are then observed to corrode to Ag{sub 2}S and after 21 days nearly full corrosion has occurred, but some with minor Ag inclusions remaining. In contrast, a bulk Ag sheet, studied in cross section, showed an adherent corrosion layer of only around 20–50 nm in thickness after over a decade of being exposed to ambient air. The results have implications for antibacterial properties and ecotoxicology of AgNP during corrosion as the dissolution and reformation of Ag particles during corrosion will likely be accompanied by the release of Ag{sup +} ions.
IN SEARCH OF IDEAL FORM- RATIO OF TRIANGULAR CHANNEL
Directory of Open Access Journals (Sweden)
B. C. DAS
2014-11-01
Full Text Available In Search of Ideal Form-Ratio of Triangular Channel. Cross-sectional form of a natural channel is a two dimensional variable which is thoroughly studied by scholars from different fields on natural sciences like hydrology, geology, geomorphology, etc. Average river channels tend to develop their channel-cross sectional form in a way to produce an approximate equilibrium between the channel and the water and sediment it transport. But how far it is deviated from the ideal cross-sectional form can only be determined by knowing the ideal form which was calculated by Hickin for rectangular channel. This ideal cross-sectional form of ‘maximum efficiency’ is virtually a theoretical one and attaining of which the river transports its water and load with least friction with its bed. ‘Ideal form ratio’ provides numerical tools for triangular channel to determine the degree of deviation of a cross-sectional form from that of an ideal one.
RKKY interaction in triangular MoS2 nanoflakes
Mastrogiuseppe, Diego; Avalos-Ovando, Oscar; Ulloa, Sergio
Transition-metal dichalcogenides (TMDs), such as MoS2, possess unique electronic and optical properties, making them promising for optospintronics. Exfoliation and CVD growth processes produce nanoflakes of different shapes, often triangular with zigzag edges. Magnetic impurities in this material interact indirectly through the TMD conduction electrons/holes. Using an effective 3-orbital tight-binding model, we study the Ruderman-Kittel-Kasuya-Yosida interaction between magnetic impurities in p-doped triangular flakes with zigzag termination. We analyze the interaction as function of impurity separation along high symmetry directions in the nanoflake, considering hybridization to different Mo orbitals, and different fillings. The interaction is anisotropic for impurities in the interior of the flake. However, when impurities lie on the edges of the crystallite, the effective exchange is Ising-like, reflecting the presence of z2-orbitals associated with edge states. Other interactions are possible by selecting impurity positions and orbital character of the states in their neighborhood. Our results can be tested with local probes, such as spin-polarized STM Supported by NSF DMR-1508325.
Herzberg Circuit and Berry's Phase in Chirality-based Coded Qubit in a Triangular Triple Quantum Dot
Hsieh, Chang-Yu; Rene, Alexandre; Hawrylak, Pawel
2011-01-01
We present a theoretical proposal for the Herzberg circuit and controlled accumulation of Berry's phase in a chirality-based coded qubit in a triangular triple quantum dot molecule with one electron spin each. The qubit is encoded in the two degenerate states of a three spin complex with total spin $S=1/2$. Using a Hubbard and Heisenberg model the Herzberg circuit encircling the degeneracy point is realized by adiabatically tuning the successive on-site energies of quantum dots and tunnel cou...
Utkin, Lev V; Chekh, Anatoly I; Zhuk, Yulia A
2016-08-01
Classification algorithms based on different forms of support vector machines (SVMs) for dealing with interval-valued training data are proposed in the paper. L2-norm and L∞-norm SVMs are used for constructing the algorithms. The main idea allowing us to represent the complex optimization problems as a set of simple linear or quadratic programming problems is to approximate the Gaussian kernel by the well-known triangular and Epanechnikov kernels. The minimax strategy is used to choose an optimal probability distribution from the set and to construct optimal separating functions. Numerical experiments illustrate the algorithms. PMID:27179616
Statistical Complexity in Traveling Densities
Lopez-Ruiz, Ricardo; Sanudo, Jaime
2009-01-01
In this work, we analyze the behavior of statistical complexity in several systems where two identical densities that travel in opposite direction cross each other. The crossing between two Gaussian, rectangular and triangular densities is studied in detail. For these three cases, the shape of the total density presenting an extreme value in complexity is found.
Alsufyani, Mohammed A.; Robin Unger
2011-01-01
Temporal triangular alopecia (TTA), also known as congenital triangular alopecia, is a nonscarring, noninflammatroy, circumscribed form of alopecia. TTA has been associated with several disorders, such as Phakomatosis Pigmentovascularis. Hair restoration surgery using follicular unit transplantation has been a successful treatment modality for TTA. Herein we report such a success that was sustained for over six years.
Clar Sextet Analysis of Triangular, Rectangular, and Honeycomb Graphene Antidot Lattices
DEFF Research Database (Denmark)
Petersen, Rene; Pedersen, Thomas Garm; Jauho, Antti-Pekka
2011-01-01
triangular, and the honeycomb lattice. It is found that the lattice geometry plays a crucial role for size of the band gap the triangular arrangement displays always a shable gap, while for the other types only particular hole separations lead to a large gap. This observation is explained using, Clear sextet...
The Preterm Infant's Use of Triangular Bids at Three Months, Adjusted Age: Two Case Studies
Hansen, Ellen Saeter
2011-01-01
This article focuses on preterm infants' early triangular capacity, restricted to the use of triangular bids in interaction with their parents. An observational setting, the Lausanne Trilogue Play (LTP), is used for studying the patterns of interaction. This is an approach focusing on the family as a whole. These observations are part of a study…
Electron sharing and anion-π recognition in molecular triangular prisms.
Schneebeli, Severin T; Frasconi, Marco; Liu, Zhichang; Wu, Yilei; Gardner, Daniel M; Strutt, Nathan L; Cheng, Chuyang; Carmieli, Raanan; Wasielewski, Michael R; Stoddart, J Fraser
2013-12-01
Stacking on a full belly: Triangular molecular prisms display electron sharing among their triangularly arranged naphthalenediimide (NDI) redox centers. Their electron-deficient cavities encapsulate linear triiodide anions, leading to the formation of supramolecular helices in the solid state. Chirality transfer is observed from the six chiral centers of the filled prisms to the single-handed helices. PMID:24227594
Collision-geometry fluctuations and triangular flow in heavy-ion collisions
Alver, B.; Roland, G.
2010-05-01
We introduce the concepts of participant triangularity and triangular flow in heavy-ion collisions, analogous to the definitions of participant eccentricity and elliptic flow. The participant triangularity characterizes the triangular anisotropy of the initial nuclear overlap geometry and arises from event-by-event fluctuations in the participant-nucleon collision points. In studies using a multiphase transport model (AMPT), a triangular flow signal is observed that is proportional to the participant triangularity and corresponds to a large third Fourier coefficient in two-particle azimuthal correlation functions. Using two-particle azimuthal correlations at large pseudorapidity separations measured by the PHOBOS and STAR experiments, we show that this Fourier component is also present in data. Ratios of the second and third Fourier coefficients in data exhibit similar trends as a function of centrality and transverse momentum as in AMPT calculations. These findings suggest a significant contribution of triangular flow to the ridge and broad away-side features observed in data. Triangular flow provides a new handle on the initial collision geometry and collective expansion dynamics in heavy-ion collisions.
26 CFR 1.1502-30 - Stock basis after certain triangular reorganizations.
2010-04-01
... 26 Internal Revenue 12 2010-04-01 2010-04-01 false Stock basis after certain triangular... (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES Basis, Stock Ownership, and Earnings and Profits Rules § 1.1502-30 Stock basis after certain triangular reorganizations. (a) Scope. This section provides...
Directory of Open Access Journals (Sweden)
Robin Unger
2011-01-01
Full Text Available Temporal triangular alopecia (TTA, also known as congenital triangular alopecia, is a nonscarring, noninflammatroy, circumscribed form of alopecia. TTA has been associated with several disorders, such as Phakomatosis Pigmentovascularis. Hair restoration surgery using follicular unit transplantation has been a successful treatment modality for TTA. Herein we report such a success that was sustained for over six years.
Constructing triangular patch by basic approximation operator plus additional interpolation operator
Institute of Scientific and Technical Information of China (English)
ZHANG Caiming; Jl Xiuhua; YANG Xingqiang
2005-01-01
A new method for constructing triangular patches is presented. The triangular patch that interpolates the given boundary curves and cross-boundary slopes is constructed by a basic approximation operator plus an additional interpolation operator. The basic approximation operator is constructed by a polynomial surface of degree five which approximates the given interpolation conditions. The additional interpolation operator is formed by the side-vertex method. The basic and the additional operators have different roles in constructing the triangular patch: the first one makes the triangular patch approximate the given interpolation conditions with a polynomial approximation precision of degree five, while the second one makes it satisfy the given interpolation conditions. The triangular patch reproduces polynomial surfaces of degree five. Comparison results of the new method with the other two methods are included.
Jordan higher all-derivable points in triangular algebras
Zhu, Jun
2011-01-01
Let ${\\mathcal{T}}$ be a triangular algebra. We say that $D=\\{D_{n}: n\\in N\\}\\subseteq L({\\mathcal{T}})$ is a Jordan higher derivable mapping at $G$ if $D_{n}(ST+TS)=\\sum_{i+j=n}(D_{i}(S)D_{j}(T)+D_{i}(T)D_{j}(S))$ for any $S,T\\in {\\mathcal{T}}$ with $ST=G$. An element $G\\in {\\mathcal{T}}$ is called a Jordan higher all-derivable point of ${\\mathcal{T}}$ if every Jordan higher derivable linear mapping $D=\\{D_{n}\\}_{n\\in N}$ at $G$ is a higher derivation. In this paper, under some mild conditions on ${\\mathcal{T}}$, we prove that some elements of ${\\mathcal{T}}$ are Jordan higher all-derivable points. This extends some results in [6] to the case of Jordan higher derivations.
Real Time Clustering of Time Series Using Triangular Potentials
Directory of Open Access Journals (Sweden)
Aldo Pacchiano
2015-01-01
Full Text Available Motivated by the problem of computing investment portfolio weightin gs we investigate various methods of clustering as alternatives to traditional mean-v ariance approaches. Such methods can have significant benefits from a practical point of view since they remove the need to invert a sample covariance matrix, which can suffer from estimation error and will almost certainly be non-stationary. The general idea is to find groups of assets w hich share similar return characteristics over time and treat each group as a singl e composite asset. We then apply inverse volatility weightings to these new composite assets. In the course of our investigation we devise a method of clustering based on triangular potentials and we present as sociated theoretical results as well as various examples based on synthetic data.
Success Factors of Biotechnology Industry Based on Triangular Fuzzy Number
Institute of Scientific and Technical Information of China (English)
Lei; LEI
2013-01-01
Based on the theory of competitive advantage and value chain, this paper establishes the indicator system, and develop the strategic framework using the fuzzy Delphi method. Then the triangular fuzzy number model is established using Fuzzy Analytic Hierarchy Process, and the key factors influencing biotechnology industry are extracted. The results show that in terms of weight, the key factors influencing the success of biotechnology industry are sequenced as follows: "open innovation capacity", "quality and cost control ability", "advanced customer-oriented product manufacturing capacity", "technology R & D personnel’s capacity", "brand image building capacity", "logistics and sales capacity", "grasping the market demand trends". The manufacturers and government decision-making body can use this as the basis, to promote the development of the biotechnology industry.
Magnetic anisotropy study of triangular-shaped Co nanostructures
Energy Technology Data Exchange (ETDEWEB)
Imperia, P. [Hahn Meitner Institut, Glienicker Strasse 100, 14109 Berlin (Germany)], E-mail: paolo.imperia@ansto.gov.au; Kandulski, W.; Kosiorek, A. [CESAR Research Center, Ludwig-Erhard-Allee 2, 53175 Bonn (Germany); Glaczynska, H. [CESAR Research Center, Ludwig-Erhard-Allee 2, 53175 Bonn (Germany); Department of Macromolecular Physics, Adam Mickiewicz University, Umultowska 85, Poznan (Poland); Maletta, H. [Hahn Meitner Institut, Glienicker Strasse 100, 14109 Berlin (Germany); Giersig, M. [CESAR Research Center, Ludwig-Erhard-Allee 2, 53175 Bonn (Germany)
2008-11-15
Atomic force microscopy (AFM), X-ray magnetic circular dichroism (XMCD), magnetic force microscopy (MFM) and vibrating sample magnetometry (VSM) have been used to measure the magnetic and geometrical characteristics of triangular-shaped Co structures of lateral size 730 nm and thickness 32 nm, prepared by nanosphere lithography (NSL). Evidence of in-plane six-fold magnetic anisotropy induced by the symmetry of the structure has been found. By means of XMCD measurements, performed at remanence after applying a pulsed field, a structure rotation angle-dependent oscillation of about 15% with a periodicity of 60 deg. has been observed for both the orbital and spin moments. Furthermore, the system exhibits the angular hysteresis effect. The magnetic measurements performed by MFM show a reduction of the magnetic configurations to only two states, one quasi-single domain Y state and second, a combination of vortex and Y state.
Magnetic phase diagrams of classical triangular and kagome antiferromagnets
Energy Technology Data Exchange (ETDEWEB)
Gvozdikova, M V [Department of Physics, Kharkov National University, 61077 Kharkov (Ukraine); Melchy, P-E; Zhitomirsky, M E, E-mail: mike.zhitomirsky@cea.fr [Service de Physique Statistique, Magnetisme et Supraconductivite, UMR-E9001 CEA-INAC/UJF, 17 rue des Martyrs, 38054 Grenoble (France)
2011-04-27
We investigate the effect of geometrical frustration on the H-T phase diagrams of the classical Heisenberg antiferromagnets on triangular and kagome lattices. The phase diagrams for the two models are obtained from large-scale Monte Carlo simulations. For the kagome antiferromagnet, thermal fluctuations are unable to lift degeneracy completely and stabilize translationally disordered multipolar phases. We find a substantial difference in the temperature scales of the order by disorder effect related to different degeneracy of the low- and the high-field classical ground states in the kagome antiferromagnet. In the low-field regime, the Kosterlitz-Thouless transition into a spin-nematic phase is produced by unbinding of half-quantum vortices.
Acoustic control study of turbofan nozzles with triangular chevrons
Directory of Open Access Journals (Sweden)
Grigore CICAN
2014-03-01
Full Text Available This paper has a small part dealing with the notion of chevron and the process that helps reducing the noise pollution. Based on the gas dynamics and the geometrical parameters of the turbofan jet engine a model of CFD data processing is created. In this process the influence of chevrons on acoustic wave intensity produced by the jet is observed by analyzing this process. A series of tests have been made on 10 si 20 lobed chevrons. The combination between them and the 7 resulting cases have been studied, namely the triangular chevrons in order to settle the influence of the geometrical parameters on the flow and on the jet acoustics. Finally the contribution of the chevrons in noise pollution reduction has been highlighted.
Notched Triangular Microstrip Antenna for Dual-Frequency Operation
Institute of Scientific and Technical Information of China (English)
江轶慧; 钟顺时
2003-01-01
A novel equilateral triangular patch with a rectangular notch etched to one radiating edge on organic magnetic substrate is proposed for dual frequency operation. Both operations of these dual frequencies arise from the perturbation of TM10 and TM11 mode by simply cutting a rectangular notch at the patch bottom. Simulations and experiments have shown the validity of this design. Using an organic magnetic material as the substrate, the antenna exhibits a broader bandwidth of 5.5% and 4.7% at dual-frequencies 1.56GHz and 2.45GHz, respectively, as well as a reduced size compared to the dual-frequency patch antennas on non-magnetic material.
Friction Factor Measurements in an Equally Spaced Triangular Tube Array
Energy Technology Data Exchange (ETDEWEB)
Vassallo P, Symolon P
2007-03-19
Friction factor data for adiabatic cross-flow of water in a staggered tube array was obtained over a Reynolds number range (based on hydraulic diameter and gap velocity) of about 10,000 to 250,000. The tubes were 12.7mm (0.5 inch) outer diameter, in a uniformly spaced triangular arrangement with a pitch-to-diameter ratio of 1.5. The friction factor was compared to several literature correlations, and was found to be best matched by the Idelchik correlation. Other correlations were found to vary significantly from the test data. Based on the test data, a new correlation is proposed for this tube bundle geometry which covers the entire Reynolds number range tested.
Simplified triangular ground plane cloak by oblique multilayer dielectrics
Institute of Scientific and Technical Information of China (English)
Wang Shen-Yun; Liu Shao-Bin
2012-01-01
Based on the effective medium theory,the triangular ground plane cloak can be realized by thin layered systems.Two solutions of parameter setting of the layered cloak are suggested to demonstrate the invisibility performance of a hybrid incoming wave.The hybrid parameters are derived from the equivalent of both anisotropies of permittivity and permeability to the alternating layers.The performance of the designed layered cloak is validated by both TM and TE wave simulations with near-field distributions and average scattering power outflows on an observation semicircle.From the simulation results,the layered cloak with both hybrid parameters and improved hybrid parameters can reflect the incoming TM/TE waves in a specular direction,and the latter behaves with a better overall invisibility performance.
Model of Vertical Product Differentiation Based on Triangular Distribution
Institute of Scientific and Technical Information of China (English)
HU Jian-bing; WANG He-ping; SHEN Yun-hong
2007-01-01
Supposing that the consumer preference complies with triangular distribution instead of uniform distribution, we establish the model of vertical product differentiation. The simulation shows that there exists stable equilibrium along with unstable equilibrium. In stable equilibrium, high quality products gain an advantage over low quality products. In unstable equilibrium, the former does not possess an apparent advantage in competition, likely to be at a disadvantage. In order to evolve from unstable equilibrium to stable equilibrium, it is necessary for firms to solve such problems as high prices and consumers' perception of scarcity on product qualities. In general, both product qualities and firm profits increase with the consuming capacity and quality perception, and the latter more rapidly.
A Generalization of the Formula for the Triangular Number of the Sum and Product of Natural Numbers
Asiru, M. A.
2008-01-01
This note generalizes the formula for the triangular number of the sum and product of two natural numbers to similar results for the triangular number of the sum and product of "r" natural numbers. The formula is applied to derive formula for the sum of an odd and an even number of consecutive triangular numbers.
Directory of Open Access Journals (Sweden)
M. Carla Aragoni
2007-01-01
Full Text Available The 3 centre-4 electrons (3c-4e and the donor/acceptor or charge-transfer models for the description of the chemical bond in linear three-body systems, such as I3– and related electron-rich (22 shell electrons systems, are comparatively discussed on the grounds of structural data from a search of the Cambridge Structural Database (CSD. Both models account for a total bond order of 1 in these systems, and while the former fits better symmetric systems, the latter describes better strongly asymmetric situations. The 3c-4e MO scheme shows that any linear system formed by three aligned closed-shell species (24 shell electrons overall has reason to exist provided that two electrons are removed from it to afford a 22 shell electrons three-body system: all combinations of three closed-shell halides and/or chalcogenides are considered here. A survey of the literature shows that most of these three-body systems exist. With some exceptions, their structural features vary continuously from the symmetric situation showing two equal bonds to very asymmetric situations in which one bond approaches to the value corresponding to a single bond and the second one to the sum of the van der Waals radii of the involved atoms. This indicates that the potential energy surface of these three-body systems is fairly flat, and that the chemical surrounding of the chalcogen/halogen atoms can play an important role in freezing different structural situations; this is well documented for the I3– anion. The existence of correlations between the two bond distances and more importantly the linearity observed for all these systems, independently on the degree of their asymmetry, support the state of hypervalency of the central atom.
Ground State of a Polaron in a Symmetric Triangular Quantum Well
Institute of Scientific and Technical Information of China (English)
ZHANG Ji-Ye; LIANG Xi-Xia
2006-01-01
@@ We study the effects of electron-phonon interaction on the electron ground state in a symmetric triangular quantum well, and calculate the ground state energy of an electron in the GaAs/Al0.96Ga0.04As triangular quantum well including the effects of the interaction between electrons and confined LO phonons by using a modified Lee-Low-Pines variational method. The electron wavefunction in the triangular well is chosen as the Airy function.The numerical results are given and discussed.
Morphological and anthropological aspects of human triangular deciduous lower first molar teeth.
Kitagawa, Y; Manabe, Y; Oyamada, J; Rokutanda, A
1996-04-01
The crown and root morphology, and bilateral occurrence of human deciduous lower first molars that exhibited a triangular occlusal outline, taken from excavated samples of Japanese, Jomonese and Iraqi origin, were investigated. The crowns of triangular teeth had smaller mesiodistal and larger buccolingual diameters than normally shaped deciduous lower first molars. An elongated buccolingual diameter was derived from the buccal projection of the distobuccal cusp and lingual projection of the portion between the metaconid and distolingual cusp. In this analysis, all triangular deciduous lower first molars in which root morphology could be observed were accompanied by additional distolingual roots. Correlation between the right- and left-hand sides of this trait was high.
Thermoviscoplastic analysis of fibrous periodic composites using triangular subvolumes
Walker, Kevin P.; Freed, Alan D.; Jordan, Eric H.
1993-01-01
The nonlinear viscoplastic behavior of fibrous periodic composites is analyzed by discretizing the unit cell into triangular subvolumes. A set of these subvolumes can be configured by the analyst to construct a representation for the unit cell of a periodic composite. In each step of the loading history, the total strain increment at any point is governed by an integral equation which applies to the entire composite. A Fourier series approximation allows the incremental stresses and strains to be determined within a unit cell of the periodic lattice. The nonlinearity arising from the viscoplastic behavior of the constituent materials comprising the composite is treated as fictitious body force in the governing integral equation. Specific numerical examples showing the stress distributions in the unit cell of a fibrous tungsten/copper metal matrix composite under viscoplastic loading conditions are given. The stress distribution resulting in the unit cell when the composite material is subjected to an overall transverse stress loading history perpendicular to the fibers is found to be highly heterogeneous, and typical homogenization techniques based on treating the stress and strain distributions within the constituent phases as homogeneous result in large errors under inelastic loading conditions.
Evidence for Triangular D_3h Symmetry in 12C
Marin-Lambarri, D J; Freer, M; Gai, M; Kokalova, Tz; Parker, D J; Wheldon, C
2014-01-01
We report a measurement of a new high spin Jp = 5- state at 22.4(0.2) MeV in 12C which fits very well to the predicted (ground state) rotational band of an oblate equilateral triangular spinning top with a D_3h symmetry characterized by the sequence 0+, 2+, 3-, 4+/-, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a D_3h symmetry was observed in triatomic molecules and it is observed here for the first time in nuclear physics. We discuss a classification of other rotation-vibration bands in 12C such as the (0+) Hoyle band and the (1-) bending mode band and suggest measurements in search of the predicted ("missing") states that may shed new light on clustering in 12C and light nuclei. In particular the observation (or non-observation) of the predicted ("missing") states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha-particle composing the Hoyle state at 7.654 MeV in 12C.
Behaviour of Lagrangian triangular mixed fluid finite elements
Indian Academy of Sciences (India)
S Gopalakrishnan; G Devi
2000-02-01
The behaviour of mixed fluid finite elements, formulated based on the Lagrangian frame of reference, is investigated to understand the effects of locking due to incompressibility and irrotational constraints. For this purpose, both linear and quadratic mixed triangular fluid elements are formulated. It is found that there exists a close relationship between the penalty finite element approach that uses reduced/selective numerical integration to alleviate locking, and the mixed finite element approach. That is, performing reduced/selective integration in the penalty approach amounts to reducing the order of pressure interpolation in the mixed finite element approach for obtaining similar results. A number of numerical experiments are performed to determine the optimum degree of interpolation of both the mean pressure and the rotational pressure in order that the twin constraints are satisfied exactly. For this purpose, the benchmark solution of the rigid rectangular tank is used. It is found that, irrespective of the degree of mean and the rotational pressure interpolation, the linear triangle mesh, with or without central bubble function (incompatible mode), locks when both the constraints are enforced simultaneously. However, for quadratic triangle, linear interpolation of the mean pressure and constant rotational pressure ensures exact satisfaction of the constraints and the mesh does not lock. Based on the results obtained from the numerical experiments, a number of important conclusions are arrived at.
Quantum electric-dipole liquid on a triangular lattice
Shen, Shi-Peng; Wu, Jia-Chuan; Song, Jun-Da; Sun, Xue-Feng; Yang, Yi-Feng; Chai, Yi-Sheng; Shang, Da-Shan; Wang, Shou-Guo; Scott, James F.; Sun, Young
2016-01-01
Geometric frustration and quantum fluctuations may prohibit the formation of long-range ordering even at the lowest temperature, and therefore liquid-like ground states could be expected. A good example is the quantum spin liquid in frustrated magnets. Geometric frustration and quantum fluctuations can happen beyond magnetic systems. Here we propose that quantum electric-dipole liquids, analogues of quantum spin liquids, could emerge in frustrated dielectrics where antiferroelectrically coupled electric dipoles reside on a triangular lattice. The quantum paraelectric hexaferrite BaFe12O19 with geometric frustration represents a promising candidate for the proposed electric-dipole liquid. We present a series of experimental lines of evidence, including dielectric permittivity, heat capacity and thermal conductivity measured down to 66 mK, to reveal the existence of an unusual liquid-like quantum phase in BaFe12O19, characterized by itinerant low-energy excitations with a small gap. The possible quantum liquids of electric dipoles in frustrated dielectrics open up a fresh playground for fundamental physics. PMID:26843363
Comparison of some isoparametric mappings for curved triangular spectral elements
Pasquetti, Richard
2016-07-01
Using the spectral element method (SEM), or more generally hp-finite elements (hp-FEM), it is possible to solve with high accuracy various kinds of problems governed by partial differential equations (PDEs), see e.g. [1,2]. However, as soon as the physical domain is not polygonal, the accuracy quickly deteriorates if curved elements are not implemented. This is the reason why various methods have been developed during the last decades, starting from the celebrated transfinite interpolation proposed for quadrangular elements in [3]. In this note we revisit this problem for triangular elements, based on the use of Fekete points for interpolations and of Gauss points for quadratures, i.e. when using the so-called Fekete-Gauss approximation. As detailed in [4], such an approach shows the so-called spectral accuracy. However, differently to the quadrangles based SEM, it does not involve diagonal mass matrices, see e.g. [5-7] and references herein for works trying to preserve this nice property that is especially useful when addressing evolution problems with an explicit time marching. In the frame of the Fekete-Gauss TSEM (T, for triangle), the present study clearly points out the importance of a good choice of the bending procedure by comparing different isoparametric mappings for the Poisson and Grad-Shafranov PDEs.
Fluid Interfaces of Triangular Containers in Reduced Gravity Environments
Guttromson, Jayleen; Manning, Robert; Collicott, Steven H.
2002-01-01
Capillary dominated fluid dynamics will be examined in a reduced-gravity environment onboard the KC-135; in particular, the behavior of the lower portion of the meniscus in triangular tank geometries. Seven clear acrylic tanks were constructed to view seven angles of the four geometries. Silicon oil with two different viscosities, 2cs and 5cs silicon oil, were used on different days of the flight. Six tanks and one control tank are filled with a certain viscosity fluid for each flight day. During each parabola, three tanks are tested at time. The experimental tanks are exchanged between parabola sets on the KC-135. The 60deg -60deg -60deg control tank is viewed throughout the flight. To gather data, two digital video cameras and one digital still camera are placed perpendicular the viewing surface. To provide a greater contrast in the meniscus, an EL backlighting sheet was used to backlight the tanks. These images and video are then digitized, passed through NASA's mini-tracker software, and compared to a theory published my M. M. Weislogel, "Fluid Interface Phenomena in a Low-Gravity Environment: Recent Results from Drop Tower Experimentation." By focusing on a lower portion of the meniscus and using longer periods of reduced gravity, this experiment may confirm that a stationary point exists on the fluid surface. This information will enable better designing of propellant management devices, especially satellite propellant refilling and gas venting. Also, biological and material processing systems in reduced gravity environments will benefit from this data.
Improved Radiation and Bandwidth of Triangular and Star Patch Antenna
Directory of Open Access Journals (Sweden)
M. Ramkumar Prabhu
2012-06-01
Full Text Available This study presents a hexagonal shape Defected Ground Structure (DGS implemented on two element triangular patch microstrip antenna array. The radiation performance of the antenna is characterized by varying the geometry and dimension of the DGS and also by locating the DGS at specific position which were simulated. Simulation and measurement results have verified that the antenna with DGS had improved the antenna without DGS. Measurement results of the hexagonal DGS have axial ratio bandwidth enhancement of 10 MHz, return loss improvement of 35%, mutual coupling reduction of 3 dB and gain enhancement of 1 dB. A new wideband and small size star shaped patch antenna fed capacitively by a small diamond shape patch is proposed. To enhance the impedance bandwidth, posts are incorporated under the patch antenna. HFSS high frequency simulator is employed to analyze the proposed antenna and simulated results on the return loss, the E- and H-plane radiation patterns and Gain of the proposed antenna are presented at various frequencies. The antenna is able to achieve in the range of 4-8.8 GHz an impedance bandwidth of 81% for return loss of less than-10 dB.
MULTIPLICATIVE GROUP AUTOMORPHISMS OF INVERTIBLE UPPER TRIANGULAR MATRICES OVER FIELDS
Institute of Scientific and Technical Information of China (English)
2000-01-01
Suppose F is a field of characteristic not 2 and F* its multiplicative group.Let T* n (F) be the multiplicative group of invertible upper triangular n × n matrices over F and ST±n(F) its subgroup {(aij) ∈ T * n(F)｜aii = +1,i}.This paper proves that f:T * n(F) → T * n(F) is a group automorphism if and only if there exist a matrix Q in T * n(F) and a field automorphism σ of F such that either σ -1 f(A) = ψ(A)QAσQ-1,A = (aij) ∈ T * n(F) or f(A) = ψ(A-1)Q[J(Aσ)-TJ]Q-1,A =(aij) ∈ T * n(F),where Aσ = (σ(aij)),A-T is the transpose inverse of A,J = n∑i=1 Ei n+1-i,and ψ :i=1 T * n(F) → F* is a homomorphism which satisfies {ψ(xIn)σ(x)｜x ∈ F*} = F* and {x ∈F*｜ψ(xIn)σ(x) = 1} = {1}.Simultaneously,they also determine the automorphisms of ST±n(F).
Institute of Scientific and Technical Information of China (English)
LIU Li-min(刘立民); LIU Han-long(刘汉龙); LIAN Chuan-jie(连传杰)
2003-01-01
The application of the finite layer & triangular prism element method to the 3D ground subsidence and stress analysis caused by mining is presented. The layer elements and the triangular prism elements have been alternatively used in the numerical simulation system, the displacement pattern, strain matrix, elastic matrix, stiffness matrix, load matrix and the stress matrix of the layer element and triangular prism element have been presented. By means of the Fortran90 programming language, a numerical simulation system based on finite layer & triangular prism element have been built up, and this system is suitable for subsidence prediction and stress analysis of all mining condition and mining methods. Comparing with the infinite element method, this approach dramatically reduces the size of the set of equations that need to be solved, and greatly reduces the amount of data preparation required. It not only saves the internal storage, and the computation time, but also decreases the cost.
Tilted resonators in a triangular elastic lattice: chirality, Bloch waves and negative refraction
Tallarico, Domenico; Movchan, Alexander B; Colquitt, Daniel J
2016-01-01
We consider a vibrating triangular mass-truss lattice whose unit cell contains a resonator of a triangular shape. The resonators are connected to the triangular lattice by trusses. Each resonator is tilted, i.e. it is rotated with respect to the triangular lattice's unit cell through an angle $\\vartheta_0$. This geometrical parameter is responsible for the emergence of a resonant mode in the Bloch spectrum for elastic waves and strongly affects the dispersive properties of the lattice. Additionally, the tilting angle $\\vartheta_0$ triggers the opening of a band gap at a Dirac-like point. We provide a physical interpretation of these phenomena and discuss the dynamical implications on elastic Bloch waves. The dispersion properties are used to design a structured interface containing tilted resonators which exhibit negative refraction and focussing, as in a "flat elastic lens".
Constructal optimization for a solid-gas reactor based on triangular element
Institute of Scientific and Technical Information of China (English)
2008-01-01
Entropy generation minimization for heat and mass transfer process in a solid-gas reactor is carried out based on constructal theory by using triangular elemental area. The aspect ratio of the triangular elemental area is optimized under constraint conditions. A number of optimal triangular elements are assembled to a new large rectangular area, which is optimised again. The procedure is repeated until the control-volume is covered, and the complete analytical results are obtained. The effects of some parameters on minimum entropy generation are analysed by nu-merical examples. The results show that smaller entropy generation can be ob-tained when the optimization for a given volume is carried out on the basis of tri-angular elements than those obtained on the basis of rectangular elements.
NATURAL SUPERCONVERGENT POINTS OF EQUILATERAL TRIANGULAR FINITE ELEMENTS-A NUMERICAL EXAMPLE
Institute of Scientific and Technical Information of China (English)
Zhi-min Zhang; Ahmed Naga
2006-01-01
A numerical test case demonstrates that the Lobatto and the Gauss points are not natural superconvergent points of the cubic and the quartic finite elements under equilateral triangular mesh for the Poisson equation.
Stress Distribution on Sandwich Structure with Triangular Grid Cores Suffered from Bending Load
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Cui Xu
2015-01-01
Full Text Available Triangular grid reinforced by carbon fiber/epoxy (CF/EP was designed and manufactured. The sandwich structure was prepared by gluing the core and composite skins. The mechanical properties of the sandwich structure were investigated by the finite element analysis (FEA and three-point bending methods. The calculated bending stiffness and core shear stress were compared to the characteristics of a honeycomb sandwich structure. The results indicated that the triangular core ultimately failed under a bending load of 11000 N; the principal stress concentration was located at the loading region; and the cracks occurred on the interface top skin and triangular core. In addition, the ultimate stress bearing of the sandwich structure was 8828 N. The experimental results showed that the carbon fiber reinforced triangular grid was much stiffer and stronger than the honeycomb structure.
Development and Applications of a Flat Triangular Element for Thin Laminated Shells
Mohan, P
1997-01-01
Finite element analysis of laminated shells using a three-noded flat triangular shell element is presented. The flat shell element is obtained by combining the Discrete Kirchhoff Theory (DKT) plate bending element and a membrane element similar to the Allman element, but derived from the Linear Strain Triangular (LST) element. Though this combination has been employed in the literature for linear static analysis of laminated plates, the results presented are not...
Ciucu, Mihai
2005-01-01
We define the correlation of holes on the triangular lattice under periodic boundary conditions and study its asymptotics as the distances between the holes grow to infinity. We prove that the joint correlation of an arbitrary collection of lattice-triangular holes of even sides satisfies, for large separations between the holes, a Coulomb law and a superposition principle that perfectly parallel the laws of two dimensional electrostatics, with physical charges corresponding to holes, and the...
Directory of Open Access Journals (Sweden)
M. Kanani Arpatapeh∗
2015-12-01
Full Text Available Let A and B be unital Banach algebras and M be a left A-module and right B-module. We consider generalized derivations associate with Hochschild 2-cocycles on triangular Banach algebra T (related to A, B and M. We characterize this new version of generalized derivations on triangular Banach algebras and we obtain some results for l 1 − direct summands of Banach algebras
Upper Triangular Matrix of Lie Algebra and a New Discrete Integrable Coupling System
Institute of Scientific and Technical Information of China (English)
YU Fa-Jun; ZHANG Hong-Qing
2007-01-01
The upper triangular matrix of Lie algebra is used to construct integrable couplings of discrete solition equations.Correspondingly,a feasible way to construct integrable couplings is presented.A nonlinear lattice soliton equation spectral problem is obtained and leads to a novel hierarchy of the nonlinear lattice equation hierarchy.It indicates that the study of integrable couplings using upper triangular matrix of Lie algebra is an important step towards constructing integrable systems.
Stress Distribution on Sandwich Structure with Triangular Grid Cores Suffered from Bending Load
Cui Xu; Huang Yanjiao; Wang Shou; Lu Chun; Fang Luping
2015-01-01
Triangular grid reinforced by carbon fiber/epoxy (CF/EP) was designed and manufactured. The sandwich structure was prepared by gluing the core and composite skins. The mechanical properties of the sandwich structure were investigated by the finite element analysis (FEA) and three-point bending methods. The calculated bending stiffness and core shear stress were compared to the characteristics of a honeycomb sandwich structure. The results indicated that the triangular core ultimately failed u...
Talabi, SO; Olunloyo, VOS; Kamiyo, OM; Collins, MW; Karayiannis, TG
2006-01-01
Triangular enclosures are typical configurations found in attic spaces of residential as well as industrial pitched-roof buildings. Previous studies on airflow within such spaces have focused on the laminar range. A numerical study has been carried out for time-dependent, two-dimensional low turbulence natural convection of air contained in the attic of a pitched roof of triangular cross-section. Two sets of boundary conditions have been considered: enclosure heated from the inclined walls an...
Triangular Alignment (TAME). A Tensor-based Approach for Higher-order Network Alignment
Energy Technology Data Exchange (ETDEWEB)
Mohammadi, Shahin [Purdue Univ., West Lafayette, IN (United States); Gleich, David F. [Purdue Univ., West Lafayette, IN (United States); Kolda, Tamara G. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Grama, Ananth [Purdue Univ., West Lafayette, IN (United States)
2015-11-01
Network alignment is an important tool with extensive applications in comparative interactomics. Traditional approaches aim to simultaneously maximize the number of conserved edges and the underlying similarity of aligned entities. We propose a novel formulation of the network alignment problem that extends topological similarity to higher-order structures and provide a new objective function that maximizes the number of aligned substructures. This objective function corresponds to an integer programming problem, which is NP-hard. Consequently, we approximate this objective function as a surrogate function whose maximization results in a tensor eigenvalue problem. Based on this formulation, we present an algorithm called Triangular AlignMEnt (TAME), which attempts to maximize the number of aligned triangles across networks. We focus on alignment of triangles because of their enrichment in complex networks; however, our formulation and resulting algorithms can be applied to general motifs. Using a case study on the NAPABench dataset, we show that TAME is capable of producing alignments with up to 99% accuracy in terms of aligned nodes. We further evaluate our method by aligning yeast and human interactomes. Our results indicate that TAME outperforms the state-of-art alignment methods both in terms of biological and topological quality of the alignments.
Analysis of the heat transfer in unsymmetrically heated triangular microchannels in slip flow regime
Institute of Scientific and Technical Information of China (English)
ZHU; Xun; LIAO; Qiang; XIN; Mingdao
2004-01-01
A theoretical analysis of heat transfer characteristics is presented for the fully developed laminar flow of the incompressible gas in the triangular microchannels heated unsymmetrically with constant axial heat flux. Through solving the energy equation with temperature jump boundary conditions in slip flow regime by virtue of a computationoriented method of the orthonormal function analysis, the dimensionless temperature profiles and the average Nusselt number for various thermal boundary conditions are obtained. The effects of Knudsen number, aspect ratio, and thermal boundary conditions on the heat transfer are discussed. The calculated results show that the orthonormal function method can be used to study the heat transfer characteristics of the unsymmetrically heated triangular microchannels. The average Nusselt number in triangular microchannels is lower for slip flow than for no-slip flow, and decreases with increasing Knudsen number. The aspect ratios and thermal boundary conditions of triangular microchannels have significant influences on the change of average Nusselt numbers with the increase in the Knudsen number. For the equilateral triangular microchannels, the decrease of the Nusselt number ratio due to temperature jump is smaller at large Knudsen number and larger at small Knudsen number on the boundary condition of bottom wall heated alone as compared with the one on the boundary condition of two heated hypotenuse walls. The correlations of the average Nusselt number with the Knudsen number for equilateral triangular microchannels are obtained.
TINITALY/01: a new Triangular Irregular Network of Italy
Directory of Open Access Journals (Sweden)
M. T. Pareschi
2007-06-01
Full Text Available A new Digital Elevation Model (DEM of the natural landforms of Italy is presented. A methodology is discussed to build a DEM over wide areas where elevation data from non-homogeneous (in density and accuracy input sources are available. The input elevation data include contour lines and spot heights derived from the Italian Regional topographic maps, satellite-based global positioning system points, ground based and radar altimetry data. Owing to the great heterogeneity of the input data density, the DEM format that better preserves the original accuracy is a Triangular Irregular Network (TIN. A Delaunay-based TIN structure is improved by using the DEST algorithm that enhances input data by evaluating inferred break-lines. Accordingly to this approach, biased distributions in slopes and elevations are absent. To prevent discontinuities at the boundary between regions characterized by data with different resolution a cubic Hermite blending weight S-shaped function is adopted. The TIN of Italy consists of 1.39×109 triangles. The average triangle area ranges from 12 to about 13000 m2 accordingly to different morphologies and different sources. About 50% of the model has a local average triangle area <500 m2. The vertical accuracy of the obtained DEM is evaluated by more than 200000 sparse control points. The overall Root Mean Square Error (RMSE is less than 3.5 m. The obtained national-scale DEM constitutes an useful support to carry out accurate geomorphological and geological investigations over large areas. The problem of choosing the best step size in deriving a grid from a TIN is then discussed and a method to quantify the loss of vertical information is presented as a function of the grid step. Some examples of DEM application are outlined. Under request, an high resolution stereo image database of the whole Italian territory (derived from the presented DEM is available to browse via internet.
Force among magnetic nanocylinders trapped in triangular arrays
Energy Technology Data Exchange (ETDEWEB)
Cisternas, E., E-mail: ecisternas@ufro.cl [Departamento de Ciencias Fisicas, Universidad de La Frontera, Casilla 54-D, Temuco (Chile); Vasquez, Y.; Vogel, E.E. [Departamento de Ciencias Fisicas, Universidad de La Frontera, Casilla 54-D, Temuco (Chile)
2012-03-15
We study the effect of the forces among magnetic nanocylinders trapped in a membrane such as those used to produce them. The interaction force between two parallel and identical magnetic nanocylinders is revisited to obtain expressions that can later be used to add them both in a discrete and a continuum approximation. At this point a particular geometry has to be assumed and we use a particular configuration reported in the literature, namely, a bundle of parallel magnetic cylinders trapped in a circular membrane. When a strong enough external magnetic field is imposed along the axis of the membrane (also along the axes of the cylinders) all magnetizations point along this direction and cylinders repel among themselves. In a first approximation we will consider a soft enough membrane so energy is mostly relaxed through a deformation of the membrane leaving the magnetization of the cylinders basically as it was in the absence of external field. Then we obtain the forces among these cylinders by two methods: one summing the contributions of a discrete number of objects and another one in which we consider a continuum distribution of them to reach larger systems. Numerical evaluation of these forces can reach 50 mdyn approximately. Such forces will act on the membrane at the positions of the magnetic cylinders; in the case of a circular silicon membrane of radius 1.0 mm the radial expansion of the membrane can be of the order of 1 nm. This effect could be larger for softer membranes. A discussion of experimental techniques to detect this phenomenon is also done followed by the proposal of a possible application. - Highlights: Black-Right-Pointing-Pointer Force among magnetic nanocylinders ordered in triangular arrays within a membrane. Black-Right-Pointing-Pointer Macroscopic effect on a membrane containing cylinders by applying an external magnetic field. Black-Right-Pointing-Pointer Membrane deformation due to magnetostatic interaction among cylinders.
Psyplot: Visualizing rectangular and triangular Climate Model Data with Python
Sommer, Philipp
2016-04-01
The development and use of climate models often requires the visualization of geo-referenced data. Creating visualizations should be fast, attractive, flexible, easily applicable and easily reproducible. There is a wide range of software tools available for visualizing raster data, but they often are inaccessible to many users (e.g. because they are difficult to use in a script or have low flexibility). In order to facilitate easy visualization of geo-referenced data, we developed a new framework called "psyplot," which can aid earth system scientists with their daily work. It is purely written in the programming language Python and primarily built upon the python packages matplotlib, cartopy and xray. The package can visualize data stored on the hard disk (e.g. NetCDF, GeoTIFF, any other file format supported by the xray package), or directly from the memory or Climate Data Operators (CDOs). Furthermore, data can be visualized on a rectangular grid (following or not following the CF Conventions) and on a triangular grid (following the CF or UGRID Conventions). Psyplot visualizes 2D scalar and vector fields, enabling the user to easily manage and format multiple plots at the same time, and to export the plots into all common picture formats and movies covered by the matplotlib package. The package can currently be used in an interactive python session or in python scripts, and will soon be developed for use with a graphical user interface (GUI). Finally, the psyplot framework enables flexible configuration, allows easy integration into other scripts that uses matplotlib, and provides a flexible foundation for further development.
Korobov, A.
2011-08-01
Discrete uniform Poisson-Voronoi tessellations of two-dimensional triangular tilings resulting from the Kolmogorov-Johnson-Mehl-Avrami (KJMA) growth of triangular islands have been studied. This shape of tiles and islands, rarely considered in the field of random tessellations, is prompted by the birth-growth process of Ir(210) faceting. The growth mode determines a triangular metric different from the Euclidean metric. Kinetic characteristics of tessellations appear to be metric sensitive, in contrast to area distributions. The latter have been studied for the variant of nuclei growth to the first impingement in addition to the conventional case of complete growth. Kiang conjecture works in both cases. The averaged number of neighbors is six for all studied densities of random tessellations, but neighbors appear to be mainly different in triangular and Euclidean metrics. Also, the applicability of the obtained results for simulating birth-growth processes when the 2D nucleation and impingements are combined with the 3D growth in the particular case of similar shape and the same orientation of growing nuclei is briefly discussed.
Korobov, A
2011-08-01
Discrete uniform Poisson-Voronoi tessellations of two-dimensional triangular tilings resulting from the Kolmogorov-Johnson-Mehl-Avrami (KJMA) growth of triangular islands have been studied. This shape of tiles and islands, rarely considered in the field of random tessellations, is prompted by the birth-growth process of Ir(210) faceting. The growth mode determines a triangular metric different from the Euclidean metric. Kinetic characteristics of tessellations appear to be metric sensitive, in contrast to area distributions. The latter have been studied for the variant of nuclei growth to the first impingement in addition to the conventional case of complete growth. Kiang conjecture works in both cases. The averaged number of neighbors is six for all studied densities of random tessellations, but neighbors appear to be mainly different in triangular and Euclidean metrics. Also, the applicability of the obtained results for simulating birth-growth processes when the 2D nucleation and impingements are combined with the 3D growth in the particular case of similar shape and the same orientation of growing nuclei is briefly discussed.
Alvarez-Ramírez, M; de Moraes, R V; Skea, J E F; Stuchi, T J
2012-01-01
We study the fourth-order stability of the triangular libration points in the absence of resonance for the three-body problem when the infinitesimal mass is affected not only by gravitation but also by light pressure from both primaries. A comprehensive summary of previous results is given, with some inaccuracies being corrected. The Lie triangle method is used to obtain the fourth-order Birkhoff normal form of the Hamiltonian, and the corresponding complex transformation to pre-normal form is given explicitly. We obtain an explicit expression for the determinant required by the Arnold-Moser theorem, and show that it is a rational function of the parameters, whose numerator is a fifth-order polynomial in the mass parameter. Particular cases where this polynomial reduces to a quartic are described. Our results reduce correctly to the purely gravitational case in the appropriate limits, and extend numerical work by previous authors.
The Interval-Valued Triangular Fuzzy Soft Set and Its Method of Dynamic Decision Making
Directory of Open Access Journals (Sweden)
Xiaoguo Chen
2014-01-01
Full Text Available A concept of interval-valued triangular fuzzy soft set is presented, and some operations of “AND,” “OR,” intersection, union and complement, and so forth are defined. Then some relative properties are discussed and several conclusions are drawn. A dynamic decision making model is built based on the definition of interval-valued triangular fuzzy soft set, in which period weight is determined by the exponential decay method. The arithmetic weighted average operator of interval-valued triangular fuzzy soft set is given by the aggregating thought, thereby aggregating interval-valued triangular fuzzy soft sets of different time-series into a collective interval-valued triangular fuzzy soft set. The formulas of selection and decision values of different objects are given; therefore the optimal decision making is achieved according to the decision values. Finally, the steps of this method are concluded, and one example is given to explain the application of the method.
Directory of Open Access Journals (Sweden)
Norhayati Abu Bakar
2015-07-01
Full Text Available In this work, we studied the structure of synthesized triangular silver nanoplates in solution and the growth of the nanoplates on a silicon surface using 3-aminopropyltrimethoxysilane (APTMS as a coupling agent. The triangular-shaped colloidal silver nanoplates were simply synthesized by a direct chemical reduction approach. We studied the three characteristic peaks of the unique optical absorbance of triangular silver nanoplates and subsequently measured an average edge length of 26 ± 1 nm. The nanoplate thickness was determined to be 7 ± 2 nm from transmission electron microscopy images. Depositing the nanoplates on a silicon surface was carried out to determine the coverage of triangular nanoplates obtained when adhesion was promoted by a coupling agent. The APTMS film assisted the attachment of the nanoplates to the silicon surface and the coverage of the nanoplates increased with increasing deposition time. The triangular silver nanoplate thin film was a monolayer and a high coverage (near complete was obtained after eight hours of exposure to the nanoplate solution. The silver film formed was shown to be a good surface-enhanced Raman scattering (SERS substrate as it gave an enormous Raman enhancement for bisphenol A (BPA.
Min, Kyong S; Zamorano, David P; Wahba, George M; Garcia, Ivan; Bhatia, Nitin; Lee, Thay Q
2014-09-01
Transforaminal pelvic fractures are high-energy injuries that are translationally and rotationally unstable. This study compared the biomechanical stability of triangular osteosynthesis vs 2-transsacral-screw fixation in the repair of a transforaminal pelvic fracture model. A transforaminal fracture model was created in 10 cadaveric lumbopelvic specimens. Five of the specimens were stabilized with triangular osteosynthesis, which consisted of unilateral L5-to-ilium lumbopelvic fixation and ipsilateral iliosacral screw fixation. The remaining 5 were stabilized with a 2-transsacral-screw fixation technique that consisted of 2 transsacral screws inserted across S1. All specimens were loaded cyclically and then loaded to failure. Translation and rotation were measured using the MicroScribe 3D digitizing system (Revware Inc, Raleigh, North Carolina). The 2-transsacral-screw group showed significantly greater stiffness than the triangular osteosynthesis group (2-transsacral-screw group, 248.7 N/mm [standard deviation, 73.9]; triangular osteosynthesis group, 125.0 N/mm [standard deviation, 66.9]; P=.02); however, ultimate load and rotational stiffness were not statistically significant. Compared with triangular osteosynthesis fixation, the use of 2 transsacral screws provides a comparable biomechanical stability profile in both translation and rotation. This newly revised 2-transsacral-screw construct offers the traumatologist an alternative method of repair for vertical shear fractures that provides biplanar stability. It also offers the advantage of percutaneous placement in either the prone or supine position.
A theoretical study of resonant tunneling characteristics in triangular double-barrier diodes
International Nuclear Information System (INIS)
Resonant tunneling characteristics of triangular double-barrier diodes have been investigated systematically in this Letter, using Airy function approach to solve time-independent Schroedinger function in triangular double-barrier structures. Originally, the exact analytic expressions of quasi-bound levels and quasi-level lifetime in symmetrical triangular double-barrier structures have been derived within the effective-mass approximation as a function of structure parameters including well width, slope width and barrier height. Based on our derived analytic expressions, numerical results show that quasi-bound levels and quasi-level lifetime vary nearly linearly with the structure parameters except that the second quasi-level lifetime changes parabolically with slope width. Furthermore, according to our improved transmission coefficient of triangular double-barrier structures under external electric field, the current densities of triangular double-barrier diodes with different slope width at 0 K have been calculated numerically. The results show that the N-shaped negative differential resistance behaviors have been observed in current-voltage characteristics and current-voltage characteristics depend on the slope width
Swarna, J; Lokeswari, T S; Smita, M; Ravindhran, R
2013-12-15
Talinum triangulare (Jacq.) Willd is an erect, succulent, perennial herb belonging to the family Portulacaceae. Under extreme environmental conditions, the plant produces betalain pigments which get accumulated in the stem region. Hence, in the present study, the betaxanthin and betacyanin patterns from different samples of T. triangulare have been investigated by applying high-performance liquid chromatography photo-diode array detection (HPLC-PDA) coupled with positive ion electro-spray mass spectrometry. Two betacyanins and two betaxanthins were identified in aqueous methanolic extract of flower, stem and leaf. Betanin, isobetanin, immonium conjugates of betalamic acid with dopamine and tyrosine were elucidated. The total betalain content was estimated by photometric analysis. In vitro antioxidant activity for the betalain extract determined by various methods revealed potent scavenging ability. The current work may possibly be considered beneficial in utilisation of the plant T. triangulare as a natural colourant in food and beverage industries. PMID:23993629
Extended particle swarm optimisation method for folding protein on triangular lattice.
Guo, Yuzhen; Wu, Zikai; Wang, Ying; Wang, Yong
2016-02-01
In this study, the authors studied the protein structure prediction problem by the two-dimensional hydrophobic-polar model on triangular lattice. Particularly the non-compact conformation was modelled to fold the amino acid sequence into a relatively larger triangular lattice, which is more biologically realistic and significant than the compact conformation. Then protein structure prediction problem was abstracted to match amino acids to lattice points. Mathematically, the problem was formulated as an integer programming and they transformed the biological problem into an optimisation problem. To solve this problem, classical particle swarm optimisation algorithm was extended by the single point adjustment strategy. Compared with square lattice, conformations on triangular lattice are more flexible in several benchmark examples. They further compared the authors' algorithm with hybrid of hill climbing and genetic algorithm. The results showed that their method was more effective in finding solution with lower energy and less running time.
Controlling light pulse in triangular quantum well nanostructure via quantum interference
International Nuclear Information System (INIS)
We study numerically the optical properties of the intersubband transitions in AlGaAs/GaAs triangular quantum well nanostructure. The Schrödinger equation is being solved numerically for this structure using homemade codes. Afterward the refractive index and the absorption coefficient are calculated for general triangular quantum well using the density matrix formalism. The density matrix equations are being solved numerically for calculation of linear susceptibility. The effect of quantum interference between spontaneous emission decays on the refractive index, absorption coefficient and group velocity is studied for purposed triangular quantum well nanostructure. The result shows the linear optical properties and group index can be controlled via quantum interference between spontaneous emission decays
Extended particle swarm optimisation method for folding protein on triangular lattice.
Guo, Yuzhen; Wu, Zikai; Wang, Ying; Wang, Yong
2016-02-01
In this study, the authors studied the protein structure prediction problem by the two-dimensional hydrophobic-polar model on triangular lattice. Particularly the non-compact conformation was modelled to fold the amino acid sequence into a relatively larger triangular lattice, which is more biologically realistic and significant than the compact conformation. Then protein structure prediction problem was abstracted to match amino acids to lattice points. Mathematically, the problem was formulated as an integer programming and they transformed the biological problem into an optimisation problem. To solve this problem, classical particle swarm optimisation algorithm was extended by the single point adjustment strategy. Compared with square lattice, conformations on triangular lattice are more flexible in several benchmark examples. They further compared the authors' algorithm with hybrid of hill climbing and genetic algorithm. The results showed that their method was more effective in finding solution with lower energy and less running time. PMID:26816397
Directory of Open Access Journals (Sweden)
Fei Chen
2015-01-01
Full Text Available A theoretical analytical method for optical properties of cavity absorber was proposed in this paper and the optical design software TracePro was used to analyze the optical properties of triangular cavity absorber. It was found that the optimal optical properties could be achieved with appropriate aperture width, depth-to-width ratio, and offset distance from focus of triangular cavity absorber. Based on the results of orthogonal experiment, the optimized triangular cavity absorber was designed. Results showed that the standard deviation of irradiance and optical efficiency of optimized designed cavity absorber were 30528 W/m2 and 89.23%, respectively. Therefore, this study could offer some valuable references for designing the parabolic trough solar concentrator in the future.
Mechanical Properties of 3-D Printed Cellular Foams with triangular cells
Bunga, Pratap Kumar
In the present work, poly lactic acid (PLA) is used as a model system to investigate the mechanical behavior of 3-D printed foams with triangular cells. Solid PLA tension and compression specimens and foams made of PLA were fabricated using fused deposition 3-D printing technique. The solid PLA tension specimens were characterized for their densities and found to be about 10% lower in density as compared to their bulk counter parts. The triangular foams had a relative density of about 64%. The relationships between the structure of the foams and its deformation behavior under compression along two in-plane directions were characterized. Furthermore, simple finite element models were developed to understand the observed deformation behavior of triangular foams.
Transformation of design formulae for feed line of triangular microstrip antenna
Mathur, Monika; Singh, Ghanshyam; Bhatnagar, S. K.; Swami, Swati; Vats, Abhijat
2016-03-01
In wireless communication system microstrip antenna is the key component. Popular shapes of patch for microstrip are rectangular, triangular and circular. A new transformation design formulae for feed line of rectangular microstrip antenna by using equivalent design concept were presented by the authors. That says one designed antenna for a given frequency on any substrate can be transformed into another substrate material for the same design frequency by simply multiply a factor ψ to the all dimensions of patch, length of feed line and some power of ψ for feed line width (where ψ is the square root of the ratio of dielectric constants of those two designs). This paper presents that the same formulae of that rectangular transformation feed line can also be applicable for triangular shape microstrip antenna transformation. The process was repeated for the triangular shape patch microstrip antenna as applied for rectangular shape and the simulation results were surprisingly the same for it by applying the same transformation formulae.
Modelling anisotropic water transport in polymer composite reinforced with aligned triangular bars
Indian Academy of Sciences (India)
Bryan Pajarito; Masatoshi Kubouchi; Saiko Aoki
2014-02-01
This work reports anisotropic water transport in a polymer composite consisting of an epoxy matrix reinforced with aligned triangular bars made of vinyl ester. By gravimetric experiments, water diffusion in resin and polymer composites were characterized. Parameters for Fickian diffusion and polymer relaxation models were determined by least-square curve fitting to the experimental data. Diffusion parameters of epoxy and vinyl ester resin were used as input during development of finite element (FE) model of polymer composite. Through transient FE diffusion analysis, anisotropic water transport in thickness direction of the polymer composite was numerically predicted and validated against experimental results. The case of using impermeable triangular bars was also numerically simulated. The diffusivity of reinforced aligned triangular bars was confirmed to affect anisotropic water transport in the composite. The results of this work suggest possible use of polymer composite for barrier and fluid removal applications.
Directory of Open Access Journals (Sweden)
Bruna Gomes Mônego
2011-04-01
Full Text Available O presente estudo investigou a influência dos traços de personalidade de acordo com o modelo dos Cinco Grandes Fatores (CGF e do amor segundo a Teoria Triangular do Amor de Sternberg na satisfação conjugal. A amostra foi composta por 192 universitários que vivenciavam um relacionamento amoroso classificado como ficante, namoro/noivado ou casamento. Os participantes responderam coletivamente à Escala Fatorial de Satisfação em Relacionamento de Casal, à Escala Triangular do Amor de Sternberg e à Bateria Fatorial de Personalidade. Os resultados indicaram padrões diferentes de correlação para cada tipo de relacionamento e o modelo de Regressão Linear Múltipla foi significativo (F=23,19, gl=10, pThis present study investigated the influence of personality traits according to the Big Five Factors (CGF model and to love according to Sternberg's Triangular Theory of Love in marital satisfaction. Sample was composed by 192 undergraduate students who experienced a loving relationship classified as an informal relationship, dating/engagement or wedding. Participants answered the "Escala Fatorial de Satisfação em Relacionamento de Casal", the Sternberg's Triangular Love Scale and the "Bateria Fatorial de Personalidade". Data showed different patterns of correlation for each type of relationship and multiple linear regression model was significant (F=23.19, df=10, p<0.001 and explained 58% of the variance. The intimacy, passion and conscientiousness constructs contributed positively to the satisfaction, while neuroticism had a negative influence. The commitment component and the other personality traits did not reach statistical significance.
Free Vibration Analysis of Sectorial Plates Using the Triangular Differential Quadrature Method
Institute of Scientific and Technical Information of China (English)
李欣; 钟宏志; 何玉红
2004-01-01
The triangular differential quadrature method was used to analyze the free vibrations of moderately thick sectorial plates. A triangular serendipity transformation was introduced to map the sectorial domain onto a unit isosceles right triangle. The first six non-dimensional frequencies of the sectorial plates were obtained for various combinations of clamped and simply supported boundary conditions. For sectorial plates with simply supported radial edges, the present results agree well with the available exact solutions and finite element solutions, demonstrating the effectiveness of the method.
Current density and poloidal magnetic field for toroidal elliptic plasmas with triangularity
International Nuclear Information System (INIS)
Changes in the poloidal magnetic field around a tokamak magnetic surface due to different values of triangularity and ellipticity are analyzed in this paper. The treatment here presented allows the determination of the poloidal magnetic field from knowledge of the toroidal current density. Different profiles of these currents are studied. Improvements in the analytic forms of the magnetic surfaces have also been found. The treatment has been performed using a recent published system of coordinates. Suitable analytic equations have been used for the elliptic magnetic surfaces with triangularity and Shafranov shift
Magnetic phase diagram of the coupled triangular spin tubes for CsCrF4
Seki, Kouichi; Okunishi, Kouichi
2015-06-01
Using Monte Carlo simulations, we explore the magnetic phase diagram of triangular spin tubes coupled with a ferromagnetic intertube interaction for CsCrF4. The planar structure of the coupled tubes is topologically equivalent to the kagome-triangular lattice, which induces nontrivial frustration effects in the system. We particularly find that, depending on the intertube coupling, various ordered phases are actually realized, such as incommensurate order, ferromagnetic order, and cuboc order, which is characterized by the noncoplanar spin structure of the 12 sublattices accompanying the spin chirality breaking. We also discuss the relevance of the results to recent experiments on CsCrF4.
Effects of Shannon entropy and electric field on polaron in RbCl triangular quantum dot
M, Tiotsop; A, J. Fotue; S, C. Kenfack; N, Issofa; H, Fotsin; L, C. Fai
2016-04-01
In this paper, the time evolution of the quantum mechanical state of a polaron is examined using the Pekar type variational method on the condition of the electric-LO-phonon strong-coupling and polar angle in RbCl triangular quantum dot. We obtain the eigenenergies, and the eigenfunctions of the ground state, and the first excited state respectively. This system in a quantum dot can be treated as a two-level quantum system qubit and the numerical calculations are performed. The effects of Shannon entropy and electric field on the polaron in the RbCl triangular quantum dot are also studied.
Institute of Scientific and Technical Information of China (English)
Jinxun Wang; Mingzhe Dong; Jun Yao
2012-01-01
Analytical expressions of relative permeability are derived for an interacting cylindrical tube bundle model.Equations for determining relative permeability curves from both the interacting uniform and interacting serial types of triangular tube bundle models are presented.Model parameters affecting the trend of relative permeability curves are discussed.Interacting triangular tube bundle models are used to history-match laboratory displacement experiments to determine the relative permeability curves of actual core samples.By adjusting model parameters to match the history of oil production and pressure drop,the estimated relative permeability curves provide a connection between the macroscopic flow behavior and the pore-scale characteristics of core samples.
Bi-stable flow in parallel triangular tube arrays with a pitch-to-diameter ratio of 1.375
Energy Technology Data Exchange (ETDEWEB)
Keogh, Daniel B., E-mail: keoghd5@tcd.ie; Meskell, Craig, E-mail: cmeskell@tcd.ie
2015-04-15
Highlights: • Study of the bi-stable flow in parallel triangular tube arrays (P/d = 1.375). • Experiments used two pressure tapped cylinders and particle image velocimetry. • Pressure signals from each of the instrumented cylinders were highly correlated. • Bi-stable flow occurs simultaneous throughout a tube array. • Bi-stable flow operates in a complex 3-dimensional arrangement. - Abstract: A study of the bi-stable flow in parallel triangular tube arrays with a pitch to diameter ratio of 1.375 has been performed. Using surface pressure data from two instrumented cylinders (one cylinder with 36 circumferential pressure taps, one cylinder with 27 axial pressure taps) and particle image velocimetry (PIV) data, the bi-stable phenomenon has been investigated. Mode-averaged PIV was performed in a draw down wind tunnel using a 125 mm tube array of 28 clear perspex tubes with a diameter of 13 mm in a Reynolds number range of 0.63–1.27×10{sup 4}. The mode of each set of image pairs was determined by simultaneously capturing the images and gathering pressure data from the surface of the test section wall. Further tests were then conducted using two instrumented cylinders mounted in a larger wind tunnel using 28 tubes with a diameter of 38 mm. The Reynolds number range was 1.84–9.19×10{sup 4}. It was found that at certain flow velocities, the pressure signals from each of the instrumented cylinders were highly correlated. Using this data, the circumferential pressure distributions across the span of an instrumented cylinder were determined for each mode using pseudo modal decomposition (PMD). From this the spanwise fluid forces were determined for each mode.
Directory of Open Access Journals (Sweden)
Dung Y. Liao
2015-06-01
Full Text Available In this study, leaves and stems of Talinum triangulare were sequentially extracted with phosphate buffer solution to obtain PTL and PTS (phosphate buffered extracts of T. triangulare leaves and stems, with 75% ethanol to obtained ETL and ETS (ethanol extracts of T. triangulare leaves and stems, or with 90°C boiling water to obtain WTL and WTS (water extracts of T. triangulare leaves and stems. We investigated the antioxidant activities of various T. triangulare extracts, analyzed the extracts' stimulations on human mononuclear cell (MNC growth and secretion of cytokines (interleukin-1 beta, interferon-γ, and tumor necrosis factor-α and nitric oxide, and then assayed their subsequent inhibitions on human leukemic U937 cell growth. Results indicated that extracts of T. triangulare showed significant antioxidant activities. Among these extracts, WTS showed the highest stimulatory effect on human MNC growth. The secretion levels of interleukin-1 beta, interferon-γ, and tumor necrosis factor-α in the conditioned medium, wherein human MNC was treated with 500 μg/mL WTS for 72 hours, were 1275, 859, and 2222 pg/mL, respectively. All conditioned media obtained from human MNCs cultured with various T. triangulare extracts showed significant inhibition against U937 cell growth of over 40%. These results suggest that T. triangulare extracts may be used in health foods for their immunomodulatory potential.
Air-guiding photonic bandgap fiber with improved triangular air-silica photonic crystal cladding
Yan, M; Shum, P
2005-01-01
We introduce a small-core air-guiding photonic crystal fiber whose cladding is made of improved air-silica photonic crystal with non-circular air holes placed in triangular lattice. The fiber achieves un-disturbed bandgap guidance over 350nm wavelength range.
Triangular metal wedges for subwavelength plasmon-polariton guiding at telecom wavelengths
DEFF Research Database (Denmark)
Boltasseva, Alexandra; Volkov, V.S.; Nielsen, Rasmus Bundgaard;
2008-01-01
We report on subwavelength plasmon-polariton guiding by triangular metal wedges at telecom wavelengths. A high-quality fabrication procedure for making gold wedge waveguides, which is also mass- production compatible offering large-scale parallel fabrication of plasmonic components, is developed...
Notes on TQFT wire models and coherence equations for SU(3) triangular cells
Coquereaux, R; Schieber, G
2010-01-01
After a summary of the TQFT wire model formalism we bridge the gap from Kuperberg equations for SU(3) spiders to Ocneanu coherence equations for systems of triangular cells on fusion graphs that describe modules associated with the fusion category of SU(3) at level k. We show how to solve these equations in a number of examples.
Neutron-scattering cross section of the S=1/2 Heisenberg triangular antiferromagnet
DEFF Research Database (Denmark)
Lefmann, K.; Hedegård, P.
1994-01-01
In this paper we use a Schwinger-boson mean-field approach to calculate the neutron-scattering cross section from the S = 1/2 antiferromagnet with nearest-neighbor isotropic Heisenberg interaction on a two-dimensional triangular lattice. We investigate two solutions for T = 0: (i) a state with long...
Scale-Invariance of Support Vector Machines based on the Triangular Kernel
Sahbi, Hichem; Fleuret, François
2002-01-01
This report focuses on the scale-invariance and the good performances of Support Vector Machines based on the triangular kernel. After a mathematica- l analysis of the scale-invariance of learning with that kernel, we illustrate its behavior with a simple 2D classification problem and compare its performances to those of a Gaussian kernel on face detection and handwritten character recognition
A natural differential calculus on Lie bialgebras with dual of triangular type
Hijligenberg, N.W. van den; Martini, R.
1995-01-01
We prove that for a specific class of Lie bialgebras, there exists a natural differential calculus. This class consists of the Lie bialgebras for which the dual Lie bialgebra is of triangular type. The differential calculus is explicitly constructed with the help of the $R$-matrix from the dual. The
Mishra, Jitendra K.; Priye, Vishnu; Rahman, B. M. A.
2016-07-01
A triangular profile multicore fiber (MCF) optical interconnect (OI) is investigated to augment performance that typically degrades at high data rates for higher order modulation in a short reach transmission system. Firstly, probability density functions (PDFs) variation with inter-core crosstalk is calculated for 8-core MCF OI with different index profile in the core and it was observed that the triangular profile MCF OI is the most crosstalk tolerant. Next, symbol error probability (SEP) for higher order quadrature phase shift keying (QPSK) modulated signal due to inter-core crosstalk is analytically obtained and their dependence on typical characteristic parameters are examined. Further, numerical simulations are carried out to compare the error performance of QPSK for step index and triangular index MCF OI by generating eye diagram at 40 Gbps per channel. Finally, it is shown that MCF OI with triangular index profile supporting QPSK has double spectral efficiency with tolerable trade off in SEP as compared with those of binary phase shift keying (BPSK) at high data rates which is scalable up to 5 Tbps.
Mohammad Afshar Kermani; Mozhdeh Afshar Kermani; Nasser Shahsavari Pour
2016-01-01
In this paper a new approach for ranking fuzzy numbers based on defuzzification is introduced. A new method for defuzzification triangular fuzzy numbers and trapezoidal fuzzy numbers based on right and left sprits of fuzzy numbers is developed first and then it is used to formulate defuzzification for fuzzy numbers. The approach is illustrated by numerical examples.
Directory of Open Access Journals (Sweden)
Siya Zhu
2015-10-01
Full Text Available Triangular nanoflake growth patterns have been commonly observed in synthesis of transition metal dichalcogenide sheets and their hybrid structures. Triangular nanoflakes not only show exceptional properties, but also can serve as building blocks for two or three dimensional structures. In this study, taking the MoS2 system as a test case, we propose a Matrix method to understand the mechanism of such unique growth pattern. Nanoflakes with different edge types are mathematically described with configuration matrices, and the total formation energy is calculated as the sum of the edge formation energies and the chemical potentials of sulfur and molybdenum. Based on energetics, we find that three triangular patterns with the different edge configurations are energetically more favorable in different ranges of the chemical potential of sulfur, which are in good agreement with experimental observations. Our algorithm has high efficiency and can deal with nanoflakes in microns which are beyond the ability of ab-initio method. This study not only elucidates the mechanism of triangular nanoflake growth patterns in experiment, but also provides a clue to control the geometric configurations in synthesis.
Prasad, D. Nagendra; Ghonge, Sudarshan; Banerjee, Souri
2016-04-01
In this paper we investigate the effect of separation of triangular metal electrodes with both convex and concave geometries, on the localization of suspended DNA molecules under the combined effect of dielectrophoresis and AC electro-osmosis through simulations using COMSOL Multiphysics. Trapping points are realized within the electrodes which are found to vary with the separation of the electrodes.
International Nuclear Information System (INIS)
Triangular nanoflake growth patterns have been commonly observed in synthesis of transition metal dichalcogenide sheets and their hybrid structures. Triangular nanoflakes not only show exceptional properties, but also can serve as building blocks for two or three dimensional structures. In this study, taking the MoS2 system as a test case, we propose a Matrix method to understand the mechanism of such unique growth pattern. Nanoflakes with different edge types are mathematically described with configuration matrices, and the total formation energy is calculated as the sum of the edge formation energies and the chemical potentials of sulfur and molybdenum. Based on energetics, we find that three triangular patterns with the different edge configurations are energetically more favorable in different ranges of the chemical potential of sulfur, which are in good agreement with experimental observations. Our algorithm has high efficiency and can deal with nanoflakes in microns which are beyond the ability of ab-initio method. This study not only elucidates the mechanism of triangular nanoflake growth patterns in experiment, but also provides a clue to control the geometric configurations in synthesis
Energy Technology Data Exchange (ETDEWEB)
Zhu, Siya; Wang, Qian, E-mail: qianwang2@pku.edu.cn [Center for Applied Physics and Technology, College of Engineering, Peking University, Beijing 100871 (China); Key Laboratory of High Energy Density Physics Simulation, and IFSA Collaborative Innovation Center, Ministry of Education, Beijing 100871 (China); Department of Materials Science and Engineering, College of Engineering, Peking University (China)
2015-10-15
Triangular nanoflake growth patterns have been commonly observed in synthesis of transition metal dichalcogenide sheets and their hybrid structures. Triangular nanoflakes not only show exceptional properties, but also can serve as building blocks for two or three dimensional structures. In this study, taking the MoS{sub 2} system as a test case, we propose a Matrix method to understand the mechanism of such unique growth pattern. Nanoflakes with different edge types are mathematically described with configuration matrices, and the total formation energy is calculated as the sum of the edge formation energies and the chemical potentials of sulfur and molybdenum. Based on energetics, we find that three triangular patterns with the different edge configurations are energetically more favorable in different ranges of the chemical potential of sulfur, which are in good agreement with experimental observations. Our algorithm has high efficiency and can deal with nanoflakes in microns which are beyond the ability of ab-initio method. This study not only elucidates the mechanism of triangular nanoflake growth patterns in experiment, but also provides a clue to control the geometric configurations in synthesis.
A numerically accurate and robust expression for bistatic scattering from a plane triangular facet
DEFF Research Database (Denmark)
Wendelboe, Gorm; Jacobsen, Finn; Bell, Judith
2006-01-01
This work is related to modeling of synthetic sonar images of naval mines or other objects. Considered here is the computation of high frequency scattering from the surface of a rigid 3D-object numerically represented by plane triangular facets. The far field scattered pressure from each facet...
A Novel Fiber Bragg Grating with Triangular Spectrum and Its Application in Strain Sensor
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
A novel fiber Bragg grating with triangular spectrum is presented. A strain sensor based on this fiber grating is proposed. Experiments showed that the sensor has advantages of high sensitivity, wider measuring range and immunity to fluctuation of the light source power.
Generation of triangular waveforms based on a microwave photonic filter with negative coefficient.
Li, Wei; Wang, Wen Ting; Sun, Wen Hui; Wang, Wei Yu; Zhu, Ning Hua
2014-06-16
We report a novel approach to generating full-duty-cycle triangular waveforms based on a microwave photonic filter (MPF) with negative coefficient. It is known that the Fourier series expansion of a triangular waveform has only odd-order harmonics. In this work, the undesired even-order harmonics are suppressed by the MPF that has a periodic transmission response. A triangular waveform at fundamental frequency can be generated by setting the bias of a Mach-Zehnder modulator (MZM) at quadrature point. However, it is found that a broadband 90° microwave phase shifter has to be used after photodetection to adjust the phases of odd-order harmonics. Alternatively, a frequency doubling triangular waveform can be generated by setting the bias of the MZM at maximum or minimum transmission point. This approach is more promising because the broadband microwave phase shifter is no longer required in this case but it is more power consuming. The proposed approach is theoretically analyzed and experimentally verified. PMID:24977593
International Nuclear Information System (INIS)
The governing equations for flow and temperature distribution in rod bundles utilizing the boundaries of the triangular mesh system are developed in the present report. The coordinate transformation is nonorthogonal and uses the natural boundaries of the mesh. Three linearly independent equations of momentum and energy are formulated in the present development
Energy Technology Data Exchange (ETDEWEB)
Shadlaghni, A.; Tavakoli, M. R.; Farzaneh, M.; Salimpour, M. R. [Isfahan University, Isfahan (Iran, Islamic Republic of)
2016-04-15
This study aimed at determining a suitable pattern to allow for a better design of the fins used in heat sinks. Flow was considered laminar and steady, and the studied heat transfer mechanism was forced convection. Considering a fixed fin volume, the shape of fin cross section and its dimensions were optimized to maximize the heat transfer rate in a given physical condition. Numerical results showed that at a constant fin base area, heat transfer rate was higher in a fin with a triangular cross section compared to the fins with rectangular or trapezoidal cross sections. Investigation of optimum dimensional ratio in triangular fins showed that an increased height/thickness ratio enhanced the heat transfer rate. The effect of vertical position of the longitudinal perforations with different cross sections but similar volume ratios on the thermal performance of triangular fins was also examined. Results showed that perforation enhanced the thermal performance of the fins. Perforations with square and circular cross sections had almost identical thermal performances and dissipated more heat compared to those with triangular perforations.
Thermal–structural analysis of ITER triangular support for dominant load verification
Energy Technology Data Exchange (ETDEWEB)
Kim, Yu-Gyeong, E-mail: aspirany@hhi.co.kr [Hyundai Heavy Industries Co., Ltd., 1000, Bangeojinsunhwando-ro, Dong-gu, Ulsan (Korea, Republic of); Hwang, Jong-Hyun; Jung, Yung-Jin [Hyundai Heavy Industries Co., Ltd., 1000, Bangeojinsunhwando-ro, Dong-gu, Ulsan (Korea, Republic of); Kim, Hyun-Soo; Ahn, Hee-Jae [National Fusion Research Institute, 113 Gwahangno, Yuseong-gu, Daejeon-si (Korea, Republic of)
2014-12-15
Highlights: • The load combination method is introduced to thermal–structural analysis for contradictive loads occurred simultaneously. • The one-way coupling analysis also conducted for thermal–structural analysis and its validity is checked by comparing with the load combination. • The dominant load for triangular support bracket is determined as the baking condition. - Abstract: The triangular support is located on the lower inner shell of vacuum vessel of ITER, which should be designed to withstand various loads such as nuclear heat, coolant pressure and so on. The appropriateness of its design is evaluated under the dominant load that could represent the most conservative condition among the design loads. In order to decide the dominant load, a valid method for thermal–structural analysis is firstly verified considering contradictory behaviors between heat and structural loads. In this paper, two approaches; one-way coupling and load combination, are introduced for thermal–structural analysis. The one-way coupling is a method generally used but has a limit to apply on contradictory conditions. The load combination could give a proper solution since it evaluates each load independently and then adds up each result linearly. Based on the results of each case, structural analysis for another load case, baking condition with incident, is conducted to find out which load is dominant for triangular support. Consequently, it is found that the baking condition is the dominant load for triangular support bracket. The proposed load combination method gives a physically reasonable solution which can be used as a reference for checking the validity of other thermal–structural analysis. It is expected that these results could be applied for manufacturing design of the triangular support under various load conditions.
Modeling and simulation of optical properties of noble metals triangular nanoprisms
Alsheheri, Soad
Gold and silver has gained huge attention across the scientific community for its applications arising from its plasmonic properties. The optical properties achieved by these materials via excitation of plasmons is very unique to these materials and used as diagnostic and therapeutic agents in the field of medicine, and as sensors in a gamut of disciplines such as energy and environmental protection to name a few. Surface plasmon resonance (SPR) properties of the gold and silver are size and shape dependent. Of the various shapes reported in literature, triangular nanoprisms has tunable optical properties in the visible and near IR region by manipulating the structural features such as thickness, edge length, and morphology of tip. To understand the effect of these parameters on dipole surface plasmon resonance we have constructed triangular silver nanoprism and sandwich of gold and triangular nanoprism using Optiwave FDTD. Silver triangular nanoprism has exhibited blue shift on introduction of truncation and the blue shift continued further with depth of truncation. Similar observations were made for increase in thickness of nanoprism. In contrast, increase in edge length of the nanoprism has introduced a blue shift in dipole surface plasmon resonance. Coupling of gold and silver as sandwich with a dielectric material has introduced two plasmon resonance peaks in the visible and near IR region. In contrast to individual silver triangular nanoprism, increasing the edge length and thickness of gold and silver has introduced a red shift. Interestingly, thickness of the dielectric layer controls the wavelength of the dipole plasmon resonance of metals in the sandwich and its strength.
Multi-frequency excitation of stiffened triangular plates for large amplitude oscillations
Askari, H.; Saadatnia, Z.; Esmailzadeh, E.; Younesian, D.
2014-10-01
Free and forced vibrations of triangular plate are investigated. Diverse types of stiffeners were attached onto the plate to suppress the undesirable large-amplitude oscillations. The governing equation of motion for a triangular plate, based on the von Kármán theory, is developed and the nonlinear ordinary differential equation of the system using Galerkin approach is obtained. Closed-form expressions for the free undamped and large-amplitude vibration of an orthotropic triangular elastic plate are presented using the two well-known analytical methods, namely, the energy balance method and the variational approach. The frequency responses in the closed-form are presented and their sensitivities with respect to the initial amplitudes are studied. An error analysis is performed and the vibration behavior, as well as the accuracy of the solution methods, is evaluated. Different types of the stiffened triangular plates are considered in order to cover a wide range of practical applications. Numerical simulations are carried out and the validity of the solution procedure is explored. It is demonstrated that the two methods of energy balance and variational approach have been quite straightforward and reliable techniques to solve those nonlinear differential equations. Subsequently, due to the importance of multiple resonant responses in engineering design, multi-frequency excitations are considered. It is assumed that three periodic forces are applied to the plate in three specific positions. The multiple time scaling method is utilized to obtain approximate solutions for the frequency resonance cases. Influences of different parameters, namely, the position of applied forces, geometry and the number of stiffeners on the frequency response of the triangular plates are examined.
Energy Technology Data Exchange (ETDEWEB)
Marin, C.; Desir, G.; Gutierrez, M.
2009-07-01
Some triangular slope facets are localized to the south of Bardenas Reales (central-west of Ebro Basin), elaborated on Tudela Formation deposits, Aragonian in age. Three of them have been dated by OSL resulting on ages of 35,588{+-}2,488 yr. BP, 35,355{+-}2,446 yr. BP and 40.185{+-}2,411 yr. BP. The origin of these facets is ought to an alternation between accumulation and incision phases produced by vegetation cover variation percentage. Those vegetation cover changes are estimated to be due to climatic changes. (Author) 21 refs.
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Absolute band gaps of a two-dimensional triangular-lattice photonic crystal are calculated with the finite-difference time-domain method in this paper.Through calculating the photonic band structures of the triangular-lattice photonic crystal consisting of Ge rods immersed in air with different shapes,it is found that a large absolute band gap of 0.098 (2c/a) can be obtained for the structures with hollow triangular Ge rods immersed in air,corresponding to 19.8% of the middle frequency.The influence of the different factors on the width of the absolute band gaps is also discussed.
Yu, Guojun
2012-10-01
In this article, comparative studies on computational accuracies and convergence rates of triangular and quadrilateral meshes are carried out in the frame work of the finite-volume method. By theoretical analysis, we conclude that the number of triangular cells needs to be 4/3 times that of quadrilateral cells to obtain similar accuracy. The conclusion is verified by a number of numerical examples. In addition, the convergence rates of the triangular meshes are found to be slower than those of the quadrilateral meshes when the same accuracy is obtained with these two mesh types. © 2012 Taylor and Francis Group, LLC.
Directory of Open Access Journals (Sweden)
Xiang-Rong Fu
2013-01-01
Full Text Available This paper presents a novel way to formulate the triangular flat shell element. The basic analytical solutions of membrane and bending plate problem for anisotropy material are studied separately. Combining with the conforming displacement along the sides and hybrid element strategy, the triangular flat shell elements based on the analytical trial functions (ATF for anisotropy material are formulated. By using the explicit integral formulae of the triangular element, the matrices used in proposed shell element are calculated efficiently. The benchmark examples showed the high accuracy and high efficiency.
The system of high frequency triangular waveform generator for mini-cyclotron
International Nuclear Information System (INIS)
This generator is designed for a super-sensitive mini-cyclotron mass spectroscope. The main difference in high frequency system design between this and ordinary cyclotron is that this system uses triangular waveform and ordinary cyclotron uses sine wave as Dee voltage. The generator's load is capacitor and it's LC resonance circuit. An electron tube works under switching signal and inductor La is considered as a constant current component in high frequency condition. It generates triangular waveform by alternatively charging and discharging a load capacitor CL with constant current. The output waveform quality depends on the constancy of the charge and discharge current and this current is affected by the shape of switching signal on grid of the electron tube
Measured and predicted root-mean-square errors in square and triangular antenna mesh facets
Fichter, W. B.
1989-01-01
Deflection shapes of square and equilateral triangular facets of two tricot-knit, gold plated molybdenum wire mesh antenna materials were measured and compared, on the basis of root mean square (rms) differences, with deflection shapes predicted by linear membrane theory, for several cases of biaxial mesh tension. The two mesh materials contained approximately 10 and 16 holes per linear inch, measured diagonally with respect to the course and wale directions. The deflection measurement system employed a non-contact eddy current proximity probe and an electromagnetic distance sensing probe in conjunction with a precision optical level. Despite experimental uncertainties, rms differences between measured and predicted deflection shapes suggest the following conclusions: that replacing flat antenna facets with facets conforming to parabolically curved structural members yields smaller rms surface error; that potential accuracy gains are greater for equilateral triangular facets than for square facets; and that linear membrane theory can be a useful tool in the design of tricot knit wire mesh antennas.
Guiding 2.94 $ \\mu $m using low-loss microstructured antiresonant triangular-core fibers
Chen, Yang; Joly, Nicolas Y; Biancalana, Fabio
2016-01-01
We introduce a new simple design of hollow-core microstructured fiber targeted to guide mid-infrared light at a wavelength 2.94 $ \\mu $m. The fiber has a triangular-core supported via silica-glass webs enclosed by a large hollow capillary tube. The fiber specific dimensions are determined based on the guiding technique, which is based on the anti-resonant mechanism. For a triangular-core with side length $100$ $ \\mu $m, the fiber has a minimum transmission loss $0.08\\pm0.005$ dB/m and dispersion 2.3 ps/km/nm at the operational wavelength 2.94 $ \\mu $m.
Indications of c-axis Charge Transport in Hole Doped Triangular Antiferromagnets
Institute of Scientific and Technical Information of China (English)
LIANG Ying; LIU Bin; FENG Shi-Ping
2004-01-01
The c-axis charge transport of the hole doped triangular antiferromagnet is investigated within the tJ model by considering the incoherent interlayer hopping.It is shown that the c-axis charge transport of the hole doped triangular antiferromagnet is essentially determined by the scattering from the in-plane fluctuation.The c-axis conductivity spectrum shows a lov-energy peak and the unusual high-energy broad band,while the c-axis resistivity is characterized by a crossover from the high temperature metallic-like behavior to the Iow temperature insulating-like behavior,which is qualitatively consistent with those of the hole doped square lattice antiferromagnet.
Surface enhanced Raman scattering, antibacterial and antifungal active triangular gold nanoparticles
Smitha, S. L.; Gopchandran, K. G.
2013-02-01
Shape controlled syntheses of gold nanoparticles have attracted a great deal of attention as their optical, electronic, magnetic and biological properties are strongly dependent on the size and shape of the particles. Here is a report on the surface enhanced Raman scattering (SERS) activity of Cinnamomum zeylanicum leaf broth reduced gold nanoparticles consisting of triangular and spherical like particles, using 2-aminothiophenol (2-ATP) and crystal violet (CV) as probe molecules. Nanoparticles prepared with a minimum leaf broth concentration, having a greater number of triangular like particles exhibit a SERS activity of the order of 107. The synthesized nanoparticles exhibit efficient antibacterial activity against the tested gram negative bacterium Escherichia coli and gram positive bacterium Staphylococcus aureus. Investigations on the antifungal activity of the synthesized nanoparticles against Aspergillus niger and Fusarium oxysporum positive is also discussed.
Dalapati, Sasanka; Addicoat, Matthew; Jin, Shangbin; Sakurai, Tsuneaki; Gao, Jia; Xu, Hong; Irle, Stephan; Seki, Shu; Jiang, Donglin
2015-07-01
Covalent organic frameworks (COFs) are an emerging class of highly ordered porous polymers with many potential applications. They are currently designed and synthesized through hexagonal and tetragonal topologies, limiting the access to and exploration of new structures and properties. Here, we report that a triangular topology can be developed for the rational design and synthesis of a new class of COFs. The triangular topology features small pore sizes down to 12 Å, which is among the smallest pores for COFs reported to date, and high π-column densities of up to 0.25 nm-2, which exceeds those of supramolecular columnar π-arrays and other COF materials. These crystalline COFs facilitate π-cloud delocalization and are highly conductive, with a hole mobility that is among the highest reported for COFs and polygraphitic ensembles.
PLASTIC ZONE OF SEMI-INFINITE CRACK INPLANAR KAGOME AND TRIANGULAR LATTICES
Institute of Scientific and Technical Information of China (English)
Xinming Qiu; Lianghong He; Yueqiang Qian; Xiong Zhang
2009-01-01
The fracture investigations of the planar lattices made of ductile cell walls are cur-rently limited to bending-dominated hexagonal honeycomb. In this paper, the plastic zones of stretching-dominated lattices, including Kagome and triangular lattices, are estimated by ana-lyzing their effective yield loci. The normalized in-plane yield loci of these two lattices are almost identical convex curves enclosed by 4 straight lines, which is almost independent of the relative density but is highly sensitive to the principal stress directions. Therefore, the plastic zones around the crack tip of Kagome and triangular are estimated to be quite different to those of the con-tinuum solid and also hexagonal lattice. The plastic zones predictions by convex yield surfaces of both lattices are validated by FE calculations, although the shear lag region caused by non-local bending effect in the Kagome lattice enlarges the plastic zone in cases of small ratio of Tp/l.
Robust band gap and half-metallicity in graphene with triangular perforations
DEFF Research Database (Denmark)
Gregersen, Søren Schou; Power, Stephen; Jauho, Antti-Pekka
2016-01-01
Ideal graphene antidot lattices are predicted to show promising band gap behavior (i.e., EG ≅ 500 meV) under carefully specified conditions. However, for the structures studied so far this behavior is critically dependent on superlattice geometry and is not robust against experimentally realistic...... disorders. Here we study a rectangular array of triangular antidots with zigzag edge geometries and show that their band gap behavior qualitatively differs from the standard behavior which is exhibited, e.g., by rectangular arrays of armchair-edged triangles. In the spin unpolarized case, zigzag......, reducing the band gaps compared to the unpolarized case. This behavior is also found to be robust in the presence of disorder. Our results highlight the possibilities of using triangular perforations in graphene to open electronic band gaps in systems with experimentally realistic levels of disorder...
Kumar, Rajneesh; Kumar, Anoop; Goel, Varun
2016-06-01
The force convective heat transfer in an equilateral triangular duct of different wall heat flux configurations was analysed for the laminar hydro-dynamically developed and thermally developing flow by the use of finite volume method. Unstructured meshing was generated by multi-block technique and set of governing equations were discretized using second-order accurate up-wind scheme and numerically solved by SIMPLE Algorithm. For ensuring accuracy, grid independence study was also done. Numerical methodology was verified by comparing results with previous work and predicted results showed good agreement with them (within error of ±5 %). The different combinations of constant heat flux boundary condition were analysed and their effect on heat transfer and fluid flow for different Reynolds number was also studied. The results of different combinations were compared with the case of force convective heat transfer in the equilateral triangular duct with constant heat flux on all three walls.
Detecting one-mode communities in bipartite networks by bipartite clustering triangular
Cui, Yaozu; Wang, Xingyuan
2016-09-01
In this paper, an algorithm is proposed to detect one-mode community structures in bipartite networks, and to deduce which one-mode community structures are weighted. After analyzing the topological properties in bipartite networks, bipartite clustering triangular is introduced. First, bipartite networks are projected into two weighted one-mode networks by bipartite clustering triangular. Then all the maximal sub-graphs from two one-mode weighted networks are extracted and the maximal sub-graphs are merged together using a weighted clustering threshold. In addition, the proposed algorithm successfully finds overlapping vertices between one-mode communities. Experimental results using some real-world network data shows that the performance of the proposed algorithm is satisfactory.
A waveless free surface flow past a submerged triangular obstacle in presence of surface tension
Directory of Open Access Journals (Sweden)
Hakima Sekhri
2016-07-01
Full Text Available We consider the Free surface flows passing a submerged triangular obstacle at the bottom of a channel. The problem is characterized by a nonlinear boundary condition on the surface of unknown configuration. The analytical exact solutions for these problems are not known. Following Dias and Vanden Broeck [6], we computed numerically the solutions via a series truncation method. These solutions depend on two parameters: the Weber number $\\alpha$ characterizing the strength of the surface tension and the angle $\\beta$ at the base characterizing the shape of the apex. Although free surface flows with surface tension admit capillary waves, it is found that solution exist only for values of the Weber number greater than $\\alpha_0$ for different configurations of the triangular obstacle.
Maximum heat transfer capacity of high temperature heat pipe with triangular grooved wick
Institute of Scientific and Technical Information of China (English)
沈妍; 张红; 许辉; 于萍; 白穜
2015-01-01
A mathematical model was developed to predict the maximum heat transfer capacity of high temperature heat pipe with triangular grooved wick. The effects of the inclination angle and geometry structure were considered in the proposed model. Maximum heat transfer capacity was also investigated experimentally. The model was validated by comparing with the experimental results. The maximum heat transfer capacity increases with the vapor core radius increasing. Compared with the inclination angle of 0°, the maximum heat transfer capacity increases at the larger inclination angle, and the change with temperature is larger. The performance of heat pipe with triangular grooved wick is greatly influenced by gravity, so it is not recommended to be applied to the dish solar heat pipe receiver.
Tailoring graphene magnetism by zigzag triangular holes: A first-principles thermodynamics study
Directory of Open Access Journals (Sweden)
Muhammad Ejaz Khan
2016-03-01
Full Text Available We discuss the thermodynamic stability and magnetic property of zigzag triangular holes (ZTHs in graphene based on the results of first-principles density functional theory calculations. We find that ZTHs with hydrogen-passivated edges in mixed sp2/sp3 configurations (z211 could be readily available at experimental thermodynamic conditions, but ZTHs with 100% sp2 hydrogen-passivation (z1 could be limitedly available at high temperature and ultra-high vacuum conditions. Graphene magnetization near the ZTHs strongly depends on the type and the size of the triangles. While metallic z1 ZTHs exhibit characteristic edge magnetism due to the same-sublattice engineering, semiconducting z211 ZTHs do show characteristic corner magnetism when the size is small <2 nm. Our findings could be useful for experimentally tailoring metal-free carbon magnetism by simply fabricating triangular holes in graphene.
Ana Paula Oliveira Amorim; Márcia Cristina Campos de Oliveira; Thiago de Azevedo Amorim; Aurea Echevarria
2013-01-01
The aim of this work is to evaluate the antioxidant activity against the radical species DPPH, the reducing capacity against Fe II ions, and the inhibitory activity on the tyrosinase enzyme of the T. triangulare. Hydromethanolic crude extract provided two fractions after the liquid/liquid partition with chloroform. The Folin-Ciocalteu method determined the total phenolic content of the crude extract (CE) and the hydromethanolic fraction (Fraction 1), resulting in a concentration of 0.5853 g/1...
Quantum Spectra and Classical Orbits in Two-Dimensional Equilateral Triangular Billiards
Institute of Scientific and Technical Information of China (English)
LIN Sheng-Lu; GAO Feng; HONG Zheng-Pin; DU Meng-Li
2005-01-01
@@ We study the correspondence between quantum spectra and classical orbits in the equilateral triangular billiards. The eigenstates of such systems are not separable functions of two variables even though the problem is exactlysolvable. We calculate the Fourier transform of a quantum spectral function and find that the positions of thepeaks match well with the lengths of the classical orbits. This is another example showing that the quantum spectral function provides a bridge between quantum and classical mechanics.
Specificity of Accounting and Tax Treatments related to Triangular Foreign Trade Transactions
Paliu-Popa, Lucia
2013-01-01
Considering the purpose of conducting any foreign trade transaction, which is generally limited to obtaining a commercial advantage by attracting foreign contribution with the smallest costs and considering the role of the accounting information and the need to involve it in decision-making due to its increased credibility and relevance in the eyes of internal and external users, in what follows we intend to develop accounting models specific to triangular foreign trade transactions in relati...
INVITRO ANTIOXIDANT AND PHYTOCHEMICAL EVAULATION OF DESMODIUM TRIANGULARE (RETZ.) MERR. ROOT
R.S. Jayaseelan; Fijesh P.Vijayan; M. Madheswaran; Suresh V; Jose Padikkala
2012-01-01
The present study was aimed to investigate the antioxidant potential of the root of Desmodium triangulare (Fabaceae). 70% Methanolic extract was screened by using in vitro by antioxidant activity screening models such as (DPPH) radical scavenging activity, ABTS radical scavenging activity, Hydroxyl radical scavenging activity, superoxide radical scavenging activity and inhibition of lipid peroxidation. The extract showed significant antioxidant activity in all the models studied. Prelimina...
Numerical Study of Thermal Radiation Effect on Confined Turbulent Free Triangular Jets
Kiyan Parham; Esmaeil Esmaeilzadeh; Amir Siahsarani; O. Phillips Agboola
2013-01-01
The present study investigates the effects of thermal radiation on turbulent free triangular jets. Finite volume method is applied for solving mass, momentum, and energy equations simultaneously. Discrete ordinate method is used to determine radiation transfer equation (RTE). Results are presented in terms of velocity, kinetic energy, and its dissipation rate fields. Results show that thermal radiation speeds the development of velocity on the jet axis and enhances kinetic energy; therefore, ...
Taoufik Ghabara; Faouzi Ghmari; M. S. Sifaoui
2007-01-01
Geometric optics approximation for emissivity from triangular surfaces was compared with exact scattering predictions from electromagnetic theory. Rigorous electromagnetic scattering theory was numerically formulated based on the differential method. We have used a numerical simulation of the emissivity of gold and tungsten for a wavelength equal 0.55 micron to explore the validity of the geometric optics. Surface parameter domains for the regions of accuracy of the geometric optics approxima...
Semi-Godunov schemes for general triangular systems of conservation laws
2006-01-01
We consider general triangular systems of conservation laws which arise in applications like multi-phase flows in porous media and are non-strictly hyperbolic. We device simple and efficient finite volume schemes of the Godunov type which are based on a local decoupling of the system into a series of single conservation laws with discontinuous coefficients and are hence termed Semi-Godunov schemes. These schemes are not based on the characte ristic structure of the system. We derive some usef...
Xu, Lin; Luo, Zhimin; Fan, Zhanxi; Zhang, Xiao; Tan, Chaoliang; Li, Hai; Zhang, Hua; Xue, Can
2014-09-01
We report the generation of triangular Ag-Pd alloy nanoprisms through a rationally designed synthetic strategy based on silver nanoprisms as sacrificial templates. The galvanic replacement between Ag nanoprisms and H2PdCl4 along with co-reduction of Ag+/Pd2+ is responsible for the formation of final prismatic Ag-Pd alloy nanostructures. Significantly, these Ag-Pd alloy nanoprisms exhibited superior electrocatalytic activity for the oxygen reduction reaction (ORR) as compared with the commercial Pd/C catalyst. Such a high catalytic activity is attributed to not only the alloyed Ag-Pd composition but also the dominant {111} facets of the triangular Ag-Pd nanoprisms. This work demonstrates the rational design of bimetallic alloy nanostructures with control of selective crystal facets that are critical to achieve high catalytic activity for fuel cell systems.We report the generation of triangular Ag-Pd alloy nanoprisms through a rationally designed synthetic strategy based on silver nanoprisms as sacrificial templates. The galvanic replacement between Ag nanoprisms and H2PdCl4 along with co-reduction of Ag+/Pd2+ is responsible for the formation of final prismatic Ag-Pd alloy nanostructures. Significantly, these Ag-Pd alloy nanoprisms exhibited superior electrocatalytic activity for the oxygen reduction reaction (ORR) as compared with the commercial Pd/C catalyst. Such a high catalytic activity is attributed to not only the alloyed Ag-Pd composition but also the dominant {111} facets of the triangular Ag-Pd nanoprisms. This work demonstrates the rational design of bimetallic alloy nanostructures with control of selective crystal facets that are critical to achieve high catalytic activity for fuel cell systems. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03600j
Bini, D. A.; Dendievel, S.; Latouche, G.; Meini, B.
2015-01-01
The Erlangian approximation of Markovian fluid queues leads to the problem of computing the matrix exponential of a subgenerator having a block-triangular, block-Toeplitz structure. To this end, we propose some algorithms which exploit the Toeplitz structure and the properties of generators. Such algorithms allow to compute the exponential of very large matrices, which would otherwise be untreatable with standard methods. We also prove interesting decay properties of the exponential of a gene...
Controlling the focusing properties of a triangular-lattice metallic photonic-crystal slab
Institute of Scientific and Technical Information of China (English)
Feng Shuai; Wang Yi-Quan; Li Zhi-Yuan; Cheng Bing-Ying; Zhang Dao-Zhong
2007-01-01
This paper studies the focusing properties of a two-dimensional photonic crystal (PC) slab consisting of a triangular lattice of metallic cylinders immersed in a dielectric background. Through the analysis of the equifrequency-surface contours and the field patterns of a point source placed in the vicinity of the PC slab, it finds that both the image distance and image quality can be controlled by simply adjusting the refractive index of the background material.
Anisotropic Hubbard model on a triangular lattice - spin dynamics in HoMnO3
Indian Academy of Sciences (India)
Saptarshi Ghosh; Avinash Singh
2008-01-01
The recent neutron scattering data for spin-wave dispersion in HoMnO3 are well-described by an anisotropic Hubbard model on a triangular lattice with a planar (XY) spin anisotropy. Best fit indicates that magnetic excitations in HoMnO3 correspond to the strong-coupling limit / > ∼ 15, with planar exchange energy = 42/ ≃ 2.5 meV and planar anisotropy ≃ 0.35 meV.
Kudanalli Nagesha, Dattatri Jois
2002-08-01
Scope and method of study. The purpose of this study was to investigate new synthetic routes to make stable CdSe and In2S 3 nanoparticles. On these newly synthesized nancolloids, the surface modification was attempted via the chalcogen sites. A mixed metal-ligand complex of Ru(bipy)2Cl2 was used for this purpose. The synthesized nanoparticles and the surface modification reaction were monitored by a changes in the UV-vis absorption spectroscopy, steady state luminescence, time resolved photoluminescence, transmission electron microscopy and nuclear magnetic resonance spectroscopy. Findings and conclusions. Stable, water-soluble CdSe nanoparticles were synthesized with narrow size distribution. Changing the ratio of metal to chalcogen during the synthesis could easily control the sizes of the nanocolloids formed. In2S3 nanoparticles were synthesized with a variety of stabilizer molecules. These particles also showed strong luminescence, which had not been reported for these materials. The surface modification of CdSe and In2S3 nanoparticles with the ruthenium complex resulted in the formation of new bands from the electronic states of the nanoparticles and the complex. The lifetime of emission increased with the modification reaction. There was due to the formation of delocalized energy levels as a consequence of modification reaction.
Directory of Open Access Journals (Sweden)
Vinous M. Hameed, Bashar Muslem Essa
2015-01-01
Full Text Available Experimental and numerical investigation has been performed in this work to evaluate the performance for triangular finned tube heat exchanger. Experimental work included designing and manufacturing of shaped triangular fins from copper material of (10mm length, (10mm height, (1mm thickness, (22 mm distance between every two fins shaped and (15mm pitch between each two of fins which are install on the straight copper tube of (2m length having (20mm inner diameter and (22mm outer diameter. The inner tube is inserted inside the Perspex tube of (54mm inner diameter and (60mm outer diameter. Cold Air and hot water are used as working fluids in the shell side and tube side, respectively. Air at various mass flow rates (0.001875 to 0.003133 kg/sec flows through annuli and water at Reynold's numbers ranging from (10376.9 to 23348.03 flows through the inner tube. Performance of (smooth and finned tube heat exchanger was investigated experimentally. Experimental results showed that the enhancement of heat dissipation for triangular finned tube is (3.252 to4.502 times than that of smooth tube respectively. Numerical simulation has been carried out on present heat exchanger to analyze flow field and heat transfer using COMSOL computational fluid dynamic (CFD package model. The comparison between experimental work and numerical results showed good agreement.
Natural convection heat transfer in vertical triangular subchannel in Zirconia-water nanofluid
Tandian, N. P.; Alkharboushi, A. A. K.; Kamajaya, K.
2015-09-01
Natural convection heat transfer in vertical triangular sub-channel has important role in cooling mechanism of the APWR and the PHWR nuclear reactors. Unfortunately, natural convection correlation equations for such geometry are scarcely available. Recent studies showed that ZrO2-water nanofluid has a good prospect to be used in the nuclear reactor technology due to its low neutron absorption cross section. Although several papers have reported transport properties of ZrO2-water nanofluids, practically there is no correlation equation for predicting natural convection heat transfer in a vertical triangular sub-channel in ZrO2-water nanofluid. Therefore, a study for finding such heat transfer correlation equation has been done by utilizing Computational Fluid Dynamics software and reported in this paper. In the study, natural convection heat transfer in a vertical triangular sub-channel has been simulated at several values of heat transfer flux within 9.1 to 30.9 kW/m2 range and ZrO2 concentrations of 0 (pure water), 0.27, and 3 volume-% of ZrO2. The study shows that the ZrO2 concentration has no significant influence to the natural convection heat transfer at those concentration levels. The obtained theoretical heat transfer correlation equations were verified through experiment, and they showed very similar results. The correlation equations are reported in this paper.
International Nuclear Information System (INIS)
In this contribution recent results on selective and precise tailoring of triangular gold nanoparticles (NPs) using ns-pulsed laser light are presented. The NPs were prepared by nanosphere lithography and subsequently tailored with ns-pulsed laser light using different fluences and wavelengths. The method is based on the size and shape dependent localized surface plasmon polariton resonance (SPR) of the NPs. We will demonstrate that the gap size between triangular NPs can be tuned from approximately 102±14 nm to 122±11 nm, due to a shape change of the NP from triangular to oblate. These morphological changes are accompanied by a significant shift of the surface plasmon resonance from λSPR=730 nm to λSPR=680 nm. Most importantly if the laser wavelength is chosen such that the dipolar SPR is excited, the hexagonal order of the NPs remains intact after irradiation, in contrast to excitation via the quadrupole SPR or within the interband transition. A tuneable gap size and the conservation of the hexagonal order of the NP array is the precondition for applications, where the NPs should serve as anchor points, e.g. for functional molecular nanowires, which can be used to utilize molecular devices.
Ding, Jian-Jiun; Huang, Ying-Wun; Lin, Pao-Yen; Pei, Soo-Chang; Chen, Hsin-Hui; Wang, Yu-Hsiang
2013-09-01
In the conventional JPEG algorithm, an image is divided into eight by eight blocks and then the 2-D DCT is applied to encode each block. In this paper, we find that, in addition to rectangular blocks, the 2-D DCT is also orthogonal in the trapezoid and triangular blocks. Therefore, instead of eight by eight blocks, we can generalize the JPEG algorithm and divide an image into trapezoid and triangular blocks according to the shapes of objects and achieve higher compression ratio. Compared with the existing shape adaptive compression algorithms, as we do not try to match the shape of each object exactly, the number of bytes used for encoding the edges can be less and the error caused from the high frequency component at the boundary can be avoided. The simulations show that, when the bit rate is fixed, our proposed algorithm can achieve higher PSNR than the JPEG algorithm and other shape adaptive algorithms. Furthermore, in addition to the 2-D DCT, we can also use our proposed method to generate the 2-D complete and orthogonal sine basis, Hartley basis, Walsh basis, and discrete polynomial basis in a trapezoid or a triangular block.
Anisotropic spin model of strong spin-orbit-coupled triangular antiferromagnets
Li, Yao-Dong; Wang, Xiaoqun; Chen, Gang
2016-07-01
Motivated by the recent experimental progress on the strong spin-orbit-coupled rare-earth triangular antiferromagnet, we analyze the highly anisotropic spin model that describes the interaction between the spin-orbit-entangled Kramers' doublet local moments on the triangular lattice. We apply the Luttinger-Tisza method, the classical Monte Carlo simulation, and the self-consistent spin wave theory to analyze the anisotropic spin Hamiltonian. The classical phase diagram includes the 120∘ state and two distinct stripe-ordered phases. The frustration is very strong and significantly suppresses the ordering temperature in the regimes close to the phase boundary between two ordered phases. Going beyond the semiclassical analysis, we include the quantum fluctuations of the spin moments within a self-consistent Dyson-Maleev spin-wave treatment. We find that the strong quantum fluctuations melt the magnetic order in the frustrated regions. We explore the magnetic excitations in the three different ordered phases as well as in strong magnetic fields. Our results provide a guidance for the future theoretical study of the generic model and are broadly relevant for strong spin-orbit-coupled triangular antiferromagnets such as YbMgGaO4, RCd3P3 , RZn3P3 , RCd3As3 , RZn3As3 , and R2O2CO3 .
Fast Tree Search for A Triangular Lattice Model of Protein Folding
Institute of Scientific and Technical Information of China (English)
Xiaomei Li; Nengchao Wang
2004-01-01
Using a triangular lattice model to study the designability of protein folding, we overcame the parity problem of previous cubic lattice model and enumerated all the sequences and compact structures on a simple two-dimensional triangular lattice model of size 4+5+6+5+4. We used two types of amino acids, hydrophobic and polar, to make up the sequences, and achieved 223+212 different sequences excluding the reverse symmetry sequences. The total string number of distinct compact structures was 219,093, excluding reflection symmetry in the self-avoiding path of length 24 triangular lattice model. Based on this model, we applied a fast search algorithm by constructing a cluster tree. The algorithm decreased the computation by computing the objective energy of non-leaf nodes. The parallel experiments proved that the fast tree search algorithm yielded an exponential speed-up in the model of size 4+5+6+5+4. Designability analysis was performed to understand the search result.
Magnetization Process of Spin-1/2 Heisenberg Antiferromagnets on a Layered Triangular Lattice
Yamamoto, Daisuke; Marmorini, Giacomo; Danshita, Ippei
2016-02-01
We study the magnetization process of the spin-1/2 antiferromagnetic Heisenberg model on a layered triangular lattice by means of a numerical cluster mean-field method with a scaling scheme (CMF+S). It has been known that antiferromagnetic spins on a two-dimensional (2D) triangular lattice with quantum fluctuations exhibit a one-third magnetization plateau in the magnetization curve under magnetic field. We demonstrate that the CMF+S quantitatively reproduces the magnetization curve including the stabilization of the plateau. We also discuss the effects of a finite interlayer coupling, which is unavoidable in real quasi-2D materials. It has been recently argued for a model of the layered-triangular-lattice compound Ba3CoSb2O9 that such interlayer coupling can induce an additional first-order transition at a strong field. We present the detailed CMF+S results for the magnetization and susceptibility curves of the fundamental Heisenberg Hamiltonian in the presence of magnetic field and weak antiferromagnetic interlayer coupling. The extra first-order transition appears as a quite small jump in the magnetization curve and a divergence in the susceptibility at a strong magnetic field ˜0.712 of the saturation field.
Robust band gap and half-metallicity in graphene with triangular perforations
Gregersen, Søren Schou; Power, Stephen R.; Jauho, Antti-Pekka
2016-06-01
Ideal graphene antidot lattices are predicted to show promising band gap behavior (i.e., EG≃500 meV) under carefully specified conditions. However, for the structures studied so far this behavior is critically dependent on superlattice geometry and is not robust against experimentally realistic disorders. Here we study a rectangular array of triangular antidots with zigzag edge geometries and show that their band gap behavior qualitatively differs from the standard behavior which is exhibited, e.g., by rectangular arrays of armchair-edged triangles. In the spin unpolarized case, zigzag-edged antidots give rise to large band gaps compared to armchair-edged antidots, irrespective of the rules which govern the existence of gaps in armchair-edged antidot lattices. In addition the zigzag-edged antidots appear more robust than armchair-edged antidots in the presence of geometrical disorder. The inclusion of spin polarization within a mean-field Hubbard approach gives rise to a large overall magnetic moment at each antidot due to the sublattice imbalance imposed by the triangular geometry. Half-metallic behavior arises from the formation of spin-split dispersive states near the Fermi energy, reducing the band gaps compared to the unpolarized case. This behavior is also found to be robust in the presence of disorder. Our results highlight the possibilities of using triangular perforations in graphene to open electronic band gaps in systems with experimentally realistic levels of disorder, and furthermore, of exploiting the strong spin dependence of the system for spintronic applications.
Oluwatoyin Orhuamen, Elizabeth; Kehinde Stephen, Olorunmaiye; Christiana Oreoluwa, Adeyemi
2012-01-01
A study of the proximate analysis of two commonly grown and consumed leafy vegetables in Nigeria “fluted pumpkin (Telfairia occidentalis) and water leaf (Talinum triangulare) was carried out. Leaves of the two vegetables were analysed in both wet and dry conditions with the aim of determining their nutrient contents and the effects of sun drying on these nutrients. The results revealed the presence of protein in the fresh leaves of Telfairia occidentalis and Talinum triangulare to be 8.31% an...
Ogbonnaya Eleazu Chinedum; Chinedum Eleazu Kate
2013-01-01
Background and Aim: Despite the pharmacological relevance of Water leaf (Talinum triangulare), there is paucity of information in literature on the effect of boiling on its pharmacopotency as well as nutritional properties. Methodology: The total chlorophyll, carotenoids, proximates, phytochemicals, minerals, vitamins and antioxidant assays of the leaves of the vegetable were performed using standard techniques. Results: The raw leaves of water leaf (Talinum triangulare) pos...
Noriyuki Hirota, Tsutomu Ando, Ryo Tanaka, Hitoshi Wada and Yoshio Sakka
2009-01-01
We studied methods of controlling the spacing between particles in the triangular lattice formed by feeble magnetic particles through induced magnetic dipole interaction. Formation of a triangular lattice is described by the balance between the magnetic force and the interaction of induced magnetic dipoles. The intensity of the magnetic force is proportional to the volume of particles V and the difference in the magnetic susceptibilities between the particles and the surrounding medium Δχ. On...
Directory of Open Access Journals (Sweden)
A. Narayan
2013-01-01
Full Text Available The oblateness and the photogravitational effects of both the primaries on the location and the stability of the triangular equilibrium points in the elliptical restricted three-body problem have been discussed. The stability of the triangular points under the photogravitational and oblateness effects of both the primaries around the binary systems Achird, Lyeten, Alpha Cen-AB, Kruger 60, and Xi-Bootis, has been studied using simulation techniques by drawing different curves of zero velocity.
Jing Liu; Yushan Chen; Haoyuan Cai; Xiaoyi Chen; Changwei Li; Cheng-Fu Yang
2015-01-01
In this study, the nanosphere lithography (NSL) method was used to fabricate hybrid Au-Ag triangular periodic nanoparticle arrays. The Au-Ag triangular periodic arrays were grown on different substrates, and the effect of the refractive index of substrates on fabrication and optical properties was systematically investigated. At first, the optical spectrum was simulated by the discrete dipole approximation (DDA) numerical method as a function of refractive indexes of substrates and mediums. S...
Energy Technology Data Exchange (ETDEWEB)
Ewing, R.E.; Saevareid, O.; Shen, J. [Texas A& M Univ., College Station, TX (United States)
1994-12-31
A multigrid algorithm for the cell-centered finite difference on equilateral triangular grids for solving second-order elliptic problems is proposed. This finite difference is a four-point star stencil in a two-dimensional domain and a five-point star stencil in a three dimensional domain. According to the authors analysis, the advantages of this finite difference are that it is an O(h{sup 2})-order accurate numerical scheme for both the solution and derivatives on equilateral triangular grids, the structure of the scheme is perhaps the simplest, and its corresponding multigrid algorithm is easily constructed with an optimal convergence rate. They are interested in relaxation of the equilateral triangular grid condition to certain general triangular grids and the application of this multigrid algorithm as a numerically reasonable preconditioner for the lowest-order Raviart-Thomas mixed triangular finite element method. Numerical test results are presented to demonstrate their analytical results and to investigate the applications of this multigrid algorithm on general triangular grids.
Jebali, Ali; Hajjar, Farzaneh Haji Esmaeil; Hekmatimoghaddam, Seyedhossein; Kazemi, Bahram; De La Fuente, Jesus M; Rashidi, Mohsen
2014-08-15
The aim of this study was to find the peptide ligands to inhibit Candida albicans secreted aspartyl proteinase 2 (Sap2). First, a ligand library, containing 300 different peptides, was constructed, and their interaction with Sap2 was separately calculated by molecular dynamic software. Second, 10 peptide ligands with the lowest intermolecular energy were selected. Then, triangular gold nanoparticles were synthesized, and separately conjugated with the peptide ligands. After synthesis, antifungal property and Sap inactivation of conjugated triangular gold nanoparticles, peptide ligands, and naked triangular gold nanoparticle were separately assessed, against thirty clinical isolates of C. albicans. In this study, we measured the uptake of conjugated and naked nanoparticles by atomic adsorption spectroscopy. This study showed that naked triangular gold nanoparticle and all conjugated triangular gold nanoparticles had high antifungal activity, but no peptide ligands had such activity. Of 300 peptide ligands, the peptide containing N-Cys-Lys-Lys-Arg-Met-Met-Lys-Ser-Met-Cys-C and its conjugate had the highest capability to inhibit Sap. Moreover, the uptake assay demonstrated that triangular gold nanoparticles conjugated with the peptide ligand had the highest uptake.
Complexation of n SO2 molecules (n = 1, 2, 3) with formaldehyde and thioformaldehyde
Azofra, Luis Miguel; Scheiner, Steve
2014-01-01
Ab initio and density functional theory calculations are used to examine complexes formed between H2CO and H2CS with 1, 2, and 3 molecules of SO2. The nature of the interactions is probed by a variety of means, including electrostatic potentials, natural bond orbital, atoms in molecules, energy decomposition, and electron density redistribution maps. The dimers are relatively strongly bound, with interaction energies exceeding 5 kcal/mol. The structures are cyclic, containing both a O/S⋯S chalcogen bond and a CH⋯O H-bond. Addition of a second SO2 molecule leads to a variety of heterotrimer structures, most of which resemble the original dimer, where the second SO2 molecule engages in a chalcogen bond with the first SO2, and a C⋯O attraction with the H2CX. Some cooperativity is apparent in the trimers and tetramers, with an attractive three-body interaction energy and shortened intermolecular distances.
Complexation of n SO{sub 2} molecules (n = 1, 2, 3) with formaldehyde and thioformaldehyde
Energy Technology Data Exchange (ETDEWEB)
Azofra, Luis Miguel [Instituto de Química Médica, CSIC, Juan de la Cierva, 3, E-28006, Madrid (Spain); Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300 (United States); Scheiner, Steve, E-mail: steve.scheiner@usu.edu [Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300 (United States)
2014-01-21
Ab initio and density functional theory calculations are used to examine complexes formed between H{sub 2}CO and H{sub 2}CS with 1, 2, and 3 molecules of SO{sub 2}. The nature of the interactions is probed by a variety of means, including electrostatic potentials, natural bond orbital, atoms in molecules, energy decomposition, and electron density redistribution maps. The dimers are relatively strongly bound, with interaction energies exceeding 5 kcal/mol. The structures are cyclic, containing both a O/S⋯S chalcogen bond and a CH⋯O H-bond. Addition of a second SO{sub 2} molecule leads to a variety of heterotrimer structures, most of which resemble the original dimer, where the second SO{sub 2} molecule engages in a chalcogen bond with the first SO{sub 2}, and a C⋯O attraction with the H{sub 2}CX. Some cooperativity is apparent in the trimers and tetramers, with an attractive three-body interaction energy and shortened intermolecular distances.
Directory of Open Access Journals (Sweden)
Vicente Cassepp-Borges
2007-01-01
Full Text Available A Escala Triangular do Amor de Sternberg (ETAS possui 45 itens relacionados à intimidade, paixão e decisão/compromisso. O objetivo deste estudo foi investigar algumas propriedades psicométricas da ETAS no Brasil. A versão brasileira da ETAS, o Teste da Identificação Familiar (FIT e um questionário sobre o relacionamento foram respondidos por 361 estudantes de três universidades. A análise fatorial da ETAS apontou para uma estrutura com três fatores e elevada consistência interna. Buscando aperfeiçoar o instrumento, o número de itens da escala foi reduzido. A nova análise fatorial indicou que as propriedades psicométricas originais foram mantidas. Foram encontradas correlações positivas entre as medidas de amor e o nível de satisfação com o relacionamento. Os resultados indicam que a versão brasileira da ETAS possui propriedades psicométricas adequadas e satisfatórias.The Sternberg's Triangular Love Scale (STLS has 45 items related to intimacy, passion, and decision/commitment. The objective of this study was to investigate some psychometric properties of the STLS in Brazil. The Brazilian version of STLS, the Test of Family Identification (FIT and a measure of satisfaction in the relationship were completed by 361 students from three universities. The factorial analysis of STLS showed a structure with 3 factors and elevated internal consistency. Seeking to improve the instrument, the number of items of the scale was reduced. The new factorial analysis indicated that the original psychometric properties were maintained. Positive correlations were found between the measurements of love and the level of satisfaction with the relationship. The results indicate that the Brazilian version of ETAS possesses adequate and satisfactory psychometric properties
Powell, R. I.
2002-01-01
Shows how integer-sided triangles can be nested, each nest having a single enclosing isosceles triangle. Brings to light what can be seen as a relatively simple generalization of Pythagoras' theorem, a result that should be readily accessible to many secondary school pupils. (Author/KHR)
Chang, Sin-Chung; Chang, Chau-Lyan; Yen, Joseph C.
2013-01-01
In the multidimensional CESE development, triangles and tetrahedra turn out to be the most natural building blocks for 2D and 3D spatial meshes. As such the CESE method is compatible with the simplest unstructured meshes and thus can be easily applied to solve problems with complex geometries. However, because the method uses space-time staggered stencils, solution decoupling may become a real nuisance in applications involving unstructured meshes. In this paper we will describe a simple and general remedy which, according to numerical experiments, has removed any possibility of solution decoupling. Moreover, in a real-world viscous flow simulation near a solid wall, one often encounters a case where a boundary with high curvature or sharp corner is surrounded by triangular/tetrahedral meshes of extremely high aspect ratio (up to 106). For such an extreme case, the spatial projection of a space-time compounded conservation element constructed using the original CESE design may become highly concave and thus its centroid (referred to as a spatial solution point) may lie far outside of the spatial projection. It could even be embedded beyond a solid wall boundary and causes serious numerical difficulties. In this paper we will also present a new procedure for constructing conservation elements and solution elements which effectively overcomes the difficulties associated with the original design. Another difficulty issue which was addressed more recently is the wellknown fact that accuracy of gradient computations involving triangular/tetrahedral grids deteriorates rapidly as the aspect ratio of grid cells increases. The root cause of this difficulty was clearly identified and several remedies to overcome it were found through a rigorous mathematical analysis. However, because of the length of the current paper and the complexity of mathematics involved, this new work will be presented in another paper.
A collapse surface for a perforated plate with an equilateral triangular array of penetrations
Energy Technology Data Exchange (ETDEWEB)
Gordon, J.L.; Jones, D.P.; Hutula, D.N.; Banas, D.
1999-02-01
This paper describes the development of incipient yield and subsequent collapse surfaces for a plate containing a large number of small circular penetrations arranged in an equilateral triangular array. The collapse surface developed here is appropriate for formulating a generic elastic-plastic flow theory for perforated materials. A unit cell is defined to characterize the mechanical response of an equilateral triangular array of penetrations. An elastic-perfectly plastic [EPP] finite element analysis [FEA] computer program is used to calculate the EPP response of the unit cell. A sufficient number of load cases are solved to define the complete incipient yield and collapse surfaces for the unit cell. A fourth order yield function is defined by squaring the Von Mises quadratic yield function and retaining only those terms that are required for the symmetry dictated by the triangular array. Curve fitting is used to determine the coefficients of the fourth order function to match the incipient yield and collapse data calculated for the unit cell by FEA. The incipient yield function in the plane of the plate incorporating the penetration pattern is shown to be almost rhomboidal in shape while the collapse curve is more elliptical. The fourth order yield function which passes through the incipient yield data possess regions where the surface is concave--a concern when developing a plasticity theory based on the function. Fitting the coefficients of the fourth order function to the collapse data results in a curve which is shown to be always convex thus having all positive outward normal vectors which is a required property for the development of plasticity flow theories.
Turbulent flow heat transfer and pressure loss in a double pipe heat exchanger with triangular fins
Directory of Open Access Journals (Sweden)
Vinous M. Hameed, Bashar Muslem Essa
2016-01-01
Full Text Available Experimental investigation of heat transfer and friction factor characteristics in a double pipe heat exchanger with triangular fins was studied. The working fluids were air, flowing in the annular pipe, and water through the inner circular tube. The test section is consisting of two parts. The first part is an insulated tube which has been manufactured from Perspex material of (54mm inner diameter, (2000mm length and (3mm thickness. The second part is an internal copper tube without or with triangular copper fins. The smooth copper tube has (2250mm long and (20mm, 22mm inner and outer diameter respectively. The triangular fins were made of the copper with thickness of 0.3mm and 10mm height. They were installed on the straight copper tube section in three different cases (32, 27, and 22 mm distance between each two successive fins and (15mm pitch between each two of fins. Air at various mass flow rates (0.001875 to 0.003133 kg/sec flows through annuli and water at Reynold's numbers ranging from (10376.9 to 23348.03 flows through the inner tube. The inlet cold air and hot water temperatures are 30oC and 70oC, respectively. The experimental results showed an increase in convective heat transfer coefficient by decreasing in distance between two fins and by increasing Reynold's number. This is due to increase in surface area. It was found that (Space=22mm gives good heat transfer enhancement.
Hu, Wen-Jun; Gong, Shou-Shu; Sheng, D. N.
2016-08-01
By using Gutzwiller projected fermionic wave functions and variational Monte Carlo technique, we study the spin-1 /2 Heisenberg model with the first-neighbor (J1), second-neighbor (J2), and additional scalar chiral interaction JχSi.(Sj×Sk) on the triangular lattice. In the nonmagnetic phase of the J1-J2 triangular model with 0.08 ≲J2/J1≲0.16 , recent density-matrix renormalization group (DMRG) studies [Zhu and White, Phys. Rev. B 92, 041105(R) (2015), 10.1103/PhysRevB.92.041105 and Hu, Gong, Zhu, and Sheng, Phys. Rev. B 92, 140403(R) (2015), 10.1103/PhysRevB.92.140403] find a possible gapped spin liquid with the signal of a competition between a chiral and a Z2 spin liquid. Motivated by the DMRG results, we consider the chiral interaction JχSi.(Sj×Sk) as a perturbation for this nonmagnetic phase. We find that with growing Jχ, the gapless U(1) Dirac spin liquid, which has the best variational energy for Jχ=0 , exhibits the energy instability towards a gapped spin liquid with nontrivial magnetic fluxes and nonzero chiral order. We calculate topological Chern number and ground-state degeneracy, both of which identify this flux state as the chiral spin liquid with fractionalized Chern number C =1 /2 and twofold topological degeneracy. Our results indicate a positive direction to stabilize a chiral spin liquid near the nonmagnetic phase of the J1-J2 triangular model.
Bayn, I; Li, L; Goldstein, J A; Schröder, T; Zhang, J; Chen, E H; Gaathon, O; Lu, M; Stein, A; Ruggiero, C A; Salzman, J; Kalish, R; Englund, D
2014-01-01
A scalable approach for integrated photonic networks in single-crystal diamond using triangular etching of bulk samples is presented. We describe designs of high quality factor (Q=2.51x10^6) photonic crystal cavities with low mode volume (Vm=1.062x({\\lambda}/n)^3), which are connected via waveguides supported by suspension structures with predicted transmission loss of only 0.05 dB. We demonstrate the fabrication of these structures using transferred single-crystal silicon hard masks and angular dry etching, yielding photonic crystal cavities in the visible spectrum with measured quality factors in excess of Q=3x103.
Triang: Soporte informático para la representación de diagramas triangulares
Martín de Jesús, Santiago
1989-01-01
RESUMEN: Se presenta un programa de ordenador para la realización de diagramas triangulares. Opcionalmente se pueden representar hasta cinco nubes de puntos diferentes en el mismo gráfico, teniendo la posibilidad de aumentar o disminuir sus dimensiones o colocar dentro una rejilla o no. Nos permite introducir los datos, bien como tantos por ciento ya calculados, o como números reales, calculando él los tanto por ciento automáticamente. Podemos grabar o leer triadas de datos de ficheros en cód...
Sobre relaciones laborales triangulares: La subcontratación y el suministro de trabajadores
José Luis Ugarte Cataldo
2006-01-01
Las relaciones laborales triangulares puede adoptar, en lo fundamental, dos modalidades: la subcontratación laboral y el suministro de trabajadores por la vía de una empresa de trabajo temporal. La primera se refiere a la situación en que una empresa, dueña de una obra o faena, contrata a otra empresa, denominada contratista, mediante un contrato civil o comercial, para que ejecute a su cuenta y riesgo, con sus propios trabajadores, un determinado trabajo o servicio, pudiendo esta última a su...
Resonance and Rectification in a Two-Dimensional Frenkel-Kontorova Model with Triangular Symmetry
Institute of Scientific and Technical Information of China (English)
YANG Yang; WANG Cang-Long; DUAN Wen-Shan; CHEN Jian-Min
2011-01-01
The mode-locking phenomena in the dc- and ac-driven overdamped two-dimensional Frenkel-Kontorova model with triangular symmetric structures are studied. The obtained results show that the transverse velocitylongitudinal velocity(vy) can occur when n is an odd number. It is also found in our simulations that the critical depinning force oscillates with the amplitude of ac-driven force, i.e., the system is dominated by the ac-driven force. The oscillatory behavior is strongly determined by the initial phase of ac force.
Peak axial-velocity decay with multi-element rectangular and triangular nozzles
Groesbeck, D. E.; Vonglahn, U. H.; Huff, R. G.
1972-01-01
The aircraft noise created by the impingement of engine exhaust jet of STOL aircraft with externally blown flaps is discussed. It was determined that the jet-flap interaction noise can be lowered by reducing the impinging velocity of the jet. The reduction must occur at a specific distance from the flap to be effective. The peak axial-velocity decay obtained with rectangular and triangular single element mixer nozzles is presented. Equations are developed for estimating the peak axial velocity decay curves for a wide range of nozzle configurations.
Voltage-Controlled Square/Triangular Wave Generator with Current Conveyors and Switching Diodes
Directory of Open Access Journals (Sweden)
Martin Janecek
2012-12-01
Full Text Available A novel relaxation oscillator based on integrating the diode-switched currents and Schmitt trigger is presented. It is derived from a known circuit with operational amplifiers where these active elements were replaced by current conveyors. The circuit employs only grounded resistances and capacitance and is suitable for high frequency square and triangular signal generation. Its frequency can be linearly and accurately controlled by voltage that is applied to a high-impedance input. Computer simulation with a model of a manufactured conveyor prototype verifies theoretic assumptions.
Institute of Scientific and Technical Information of China (English)
GAO Wei; DUAN Ya-li; LIU Ru-xun
2009-01-01
In this article a finite volume method is proposed to solve viscous incompressible Navier-Stokes equations in two-dimensional regions with corners and curved boundaries. A hybrid collocated-grid variable arrangement is adopted, in which the velocity and pressure are stored at the centroid and the circumcenters of the triangular control cell, respectively. The cell flux is defined at the mid-point of the cell face. Second-order implicit time integration schemes are used for convection and diffusion terms. The second-order upwind scheme is used for convection fluxes. The present method is validated by results of several viscous flows.
INVITRO ANTIOXIDANT AND PHYTOCHEMICAL EVAULATION OF DESMODIUM TRIANGULARE (RETZ. MERR. ROOT
Directory of Open Access Journals (Sweden)
R.S. Jayaseelan
2012-04-01
Full Text Available The present study was aimed to investigate the antioxidant potential of the root of Desmodium triangulare (Fabaceae. 70% Methanolic extract was screened by using in vitro by antioxidant activity screening models such as (DPPH radical scavenging activity, ABTS radical scavenging activity, Hydroxyl radical scavenging activity, superoxide radical scavenging activity and inhibition of lipid peroxidation. The extract showed significant antioxidant activity in all the models studied. Preliminary phytochemical analysis of the extract were also carried out and revealed the presence of alkaloids, steroids, glycosides, saponins, fixed oils and fatty acids,
Directory of Open Access Journals (Sweden)
Nutan Singh
2013-11-01
Full Text Available This paper deals with the stability of triangular Lagrangian points in the elliptical restricted three body problem, under the effect of radiation pressure stemming from the more massive primary on the infinitesimal. We adopted a set of rotating pulsating axes centered at the centre of mass of the two primaries Sun and Jupiter. We have exploited method of averaging used by Grebenikov, throughout the analysis of stability of the system. The critical mass ratio depends on the radiation pressure, eccentricity and the range of stability decreases as the radiation parameter increases. Keywords: Dynamical system, elliptical restricted three body problems, lagrangian points, radiation pressure, and stability.
Analysis of Syetem Reliability in Manufacturing Cell Based on Triangular Fuzzy Number
Institute of Scientific and Technical Information of China (English)
ZHANG Caibo; HAN Botang; SUN Changsen; XU Chunjie
2006-01-01
Due to lacking of test-data and field-data in reliability research during the design stage of manufacturing cell system. The degree of manufacturing cell system reliability research is increased. In order to deal with the deficient data and the uncertainty occurred from analysis and judgment, the paper discussed a method for studying reliability of manufacturing cell system through the analysis of fuzzy fault tree, which was based on triangular fuzzy number. At last, calculation case indicated that it would have great significance for ascertaining reliability index, maintenance and establishing keeping strategy towards manufacturing cell system.
A New Accurate yet Simple Shear Flexible Triangular Plate Element with Linear Bending Strains
DEFF Research Database (Denmark)
Damkilde, Lars; Pedersen, Ronnie
2010-01-01
The paper describes a new shear flexible triangular element. The formulation is based on displacement interpolation of the transverse displacement of the midsurface and the rotations of the cross-sections, and the element is fully compatible. The basic principle is to use a so-called balanced...... locking, which otherwise has to be eliminated by remedies as reduced or selective integration. The element has been tested in different ways and the convergence rate and accuracy are good. By introducing a small incompatibility the degrees of freedom can be reduced from 22 to 18 and the results are...
Spin superfluidity in the anisotropic XY model in the triangular lattice
Lima, L. S.
2016-07-01
We use the SU(3) Schwinger's boson theory to study the spin transport properties in the two-dimensional anisotropic frustrated Heisenberg model in the triangular lattice at T=0. We have investigated the behavior of the spin conductivity for this model which presents an single-ion anisotropy. We study the spin transport in the Bose-Einstein condensation regime where we have that the tz bosons are condensed and the following condition is valid: = = t . Our results show a metallic spin transport for ω > 0 and a superfluid spin transport in the limit of DC conductivity, ω → 0 , where σ(ω) tends to infinity in this limit of ω.
Indian Academy of Sciences (India)
S Nayak; S Chakraverty
2015-10-01
In this paper, neutron diffusion equation of a triangular homogeneous bare reactor with uncertain parameters has been investigated. Here the involved parameters viz. geometry of the reactor, diffusion coefficient and absorption coefficient, etc. are uncertain and these are considered as fuzzy. Fuzzy values are handled through limit method which was defined for interval computations. The concept of fuzziness is hybridised with traditional finite element method to propose fuzzy finite element method. The proposed fuzzy finite element method has been used to obtain the uncertain eigenvalues of the said problem. Further these uncertain eigenvalues are compared with the traditional finite element method in special cases.
Ascent sequences and upper triangular matrices containing non-negative integers
Dukes, Mark
2009-01-01
This paper presents a bijection between ascent sequences and upper triangular matrices whose non-negative entries are such that all rows and columns contain at least one non-zero entry. We show the equivalence of several natural statistics on these structures under this bijection and prove that some of these statistics are equidistributed. Several special classes of matrices are shown to have simple formulations in terms of ascent sequences. Binary matrices are shown to correspond to ascent sequences with no two adjacent entries the same. Bidiagonal matrices are shown to be related to order-consecutive set partitions and a simple condition on the ascent sequences generate this class.
The density of states for an antiferromagnetic Ising model on a triangular lattice
Institute of Scientific and Technical Information of China (English)
XIA Kai; YAO Xiao-yan; LIU Jun-ming
2007-01-01
The Wang-Landau algorithm is an efficient Monte Carlo approach to the density of states of a statistical mechanics system.The estimation of state density would allow the computation of thermodynamic properties of the system over the whole temperature range.We apply this sampling method to study the phase transitions in a triangular Ising model.The entropy of the lattice at zero temperature as well as other thermodynamic properties is computed.The calculated thermodynamic properties are explained in the context of the magnetic phase transition.
Hofstadter problem on the honeycomb and triangular lattices: Bethe ansatz solution
Kohmoto, M.; Sedrakyan, A.
2006-06-01
We consider Bloch electrons on the honeycomb lattice under a uniform magnetic field with 2πp/q flux per cell. It is shown that the problem factorizes to two triangular lattices. Treating magnetic translations as a Heisenberg-Weyl group and by the use of its irreducible representation on the space of theta functions, we find a nested set of Bethe equations, which determine the eigenstates and energy spectrum. The Bethe equations have simple form which allows us to consider them further in the limit p,q→∞ by the technique of thermodynamic Bethe ansatz and analyze the Hofstadter problem for the irrational flux.
Hofstadter Problem on the Honeycomb and Triangular Lattices: Bethe Ansatz Solution
Kohmoto, M.; Sedrakyan, A.
2006-01-01
We consider Bloch electrons on the honeycomb lattice under a uniform magnetic field with $2 \\pi p/q$ flux per cell. It is shown that the problem factorizes to two triangular lattices. Treating magnetic translations as Heisenberg-Weyl group and by the use of its irreducible representation on the space of theta functions, we find a nested set of Bethe equations, which determine the eigenstates and energy spectrum. The Bethe equations have simple form which allows to consider them further in the...
Algebraic Bethe ansatz for the XXX chain with triangular boundaries and Gaudin model
António, N Cirilo; Salom, I
2014-01-01
We implement fully the algebraic Bethe ansatz for the XXX Heisenberg spin chain in the case when both boundary matrices can be brought to the upper-triangular form. We define the Bethe vectors which yield the strikingly simple expression for the off shell action of the transfer matrix, deriving the spectrum and the corresponding Bethe equations. We explore further these results by obtaining the off shell action of the generating function of the Gaudin Hamiltonians on the Bethe vectors through the so-called quasi-classical limit.
Algebraic Bethe ansatz for the XXX chain with triangular boundaries and Gaudin model
Cirilo António, N.; Manojlović, N.; Salom, I.
2014-12-01
We implement fully the algebraic Bethe ansatz for the XXX Heisenberg spin chain in the case when both boundary matrices can be brought to the upper-triangular form. We define the Bethe vectors which yield the strikingly simple expression for the off shell action of the transfer matrix, deriving the spectrum and the relevant Bethe equations. We explore further these results by obtaining the off shell action of the generating function of the Gaudin Hamiltonians on the corresponding Bethe vectors through the so-called quasi-classical limit. Moreover, this action is as simple as it could possibly be, yielding the spectrum and the Bethe equations of the Gaudin model.
Comparison of magnetoresistances of triangular and rectangular ballistic graphene npn junctions
Morikawa, Sei; Masubuchi, Satroru; Watanabe, Kenji; Taniguchi, Takashi; Machida, Tomoki
2016-10-01
We compared the magnetotransport properties of ballistic graphene npn junctions with two different geometries. We found that a rectangular npn junction shows a positive magnetoresistance around zero magnetic field; this finding can be explained by the suppression of Klein tunneling in a finite magnetic field. In contrast, a triangular npn junction shows a negative magnetoresistance because the transmission is enhanced in a commensurability magnetic field where the ballistic carriers in a cyclotron motion are injected perpendicularly to both the np and pn interfaces. These results suggest possibilities for manipulating ballistic carrier trajectories through the designs of local-gate geometries.
Ashkarran, Ali Akbar
2016-08-01
Triangular silver nanostructures represent a novel class of nanomaterials with tunable surface plasmon resonance (SPR). By controlling the size and geometry of these structures, their SPR peaks could be tuned from the visible to the near-infrared region with numerous applications in optoelectronic, sensors, nanomedicine and specially cancer diagnosis and treatment. In this study, triangular silver nanostructures were prepared by photoinducing of spherical silver nanoparticles (NPs) with an average diameter of 10 nm. Transmission electron microscopy (TEM) and ultra violet visible (UV-Vis) spectroscopy were used to characterize silver triangles. We have found that uniform triangular silver nanostructures can be obtained using an appropriate visible-light illumination to the primary spherical silver NPs. TEM images indicated that formation of triangular structures depends on the intensity of light source. The effect of intensity of visible-light source on the geometry and size distribution of silver triangles was investigated. It was found that formation of triangular structures in addition to their size and shape evolution strongly depends on the intensity of the light illumination. Furthermore, a comparative study on the antibacterial activities of silver triangles of different sizes reveals that silver triangles experience a size-dependent interaction with the gram-negative Escherichia coli bacteria.
A mass-redistributed finite element method (MR-FEM) for acoustic problems using triangular mesh
He, Z. C.; Li, Eric; Liu, G. R.; Li, G. Y.; Cheng, A. G.
2016-10-01
The accuracy of numerical results using standard finite element method (FEM) in acoustic problems will deteriorate with increasing frequency due to the "dispersion error". Such dispersion error depends on the balance between the "stiffness" and "mass" of discretization equation systems. This paper reports an improved finite element method (FEM) for solving acoustic problems by re-distributing the mass in the mass matrix to "tune" the balance, aiming to minimize the dispersion errors. This is done by shifting the integration point locations when computing the entries of the mass matrix, while ensuring the mass conservation. The new method is verified through the detailed numerical error analysis, and a strategy is also proposed for the best mass redistribution in terms of minimizing dispersion error. The relative dispersion error of present mass-redistributed finite element method (MR-FEM) is found to be much smaller than the FEM solution, in both theoretical prediction and numerical examination. The present MR-FEM works well by using the linear triangular elements that can be generated automatically, which enables automation in computation and saving computational cost in mesh generation. Numerical examples demonstrate the advantages of MR-FEM, in comparison with the standard FEM using the same triangular meshes and quadrilateral meshes.
Directory of Open Access Journals (Sweden)
Shanzhi Xu
2016-04-01
Full Text Available In order to measure the impedance variation process in electrolyte solutions, a method of triangular waveform voltage excitation is investigated together with principal component analysis (PCA. Using triangular waveform voltage as the excitation signal, the response current during one duty cycle is sampled to construct a measurement vector. The measurement matrix is then constructed by the measurement vectors obtained from different measurements. After being processed by PCA, the changing information of solution impedance is contained in the loading vectors while the response current and noise information is contained in the score vectors. The measurement results of impedance variation by the proposed signal processing method are independent of the equivalent impedance model. The noise-induced problems encountered during equivalent impedance calculation are therefore avoided, and the real-time variation information of noise in the electrode-electrolyte interface can be extracted at the same time. Planar-interdigitated electrodes are experimentally tested for monitoring the KCl concentration variation process. Experimental results indicate that the measured impedance variation curve reflects the changing process of solution conductivity, and the amplitude distribution of the noise during one duty cycle can be utilized to analyze the contact conditions of the electrode and electrolyte interface.
Brilhaus, Dominik; Bräutigam, Andrea; Mettler-Altmann, Tabea; Winter, Klaus; Weber, Andreas P M
2016-01-01
Drought tolerance is a key factor for agriculture in the 21st century as it is a major determinant of plant survival in natural ecosystems as well as crop productivity. Plants have evolved a range of mechanisms to cope with drought, including a specialized type of photosynthesis termed Crassulacean acid metabolism (CAM). CAM is associated with stomatal closure during the day as atmospheric CO2 is assimilated primarily during the night, thus reducing transpirational water loss. The tropical herbaceous perennial species Talinum triangulare is capable of transitioning, in a facultative, reversible manner, from C3 photosynthesis to weakly expressed CAM in response to drought stress. The transcriptional regulation of this transition has been studied. Combining mRNA-Seq with targeted metabolite measurements, we found highly elevated levels of CAM-cycle enzyme transcripts and their metabolic products in T. triangulare leaves upon water deprivation. The carbohydrate metabolism is rewired to reduce the use of reserves for growth to support the CAM-cycle and the synthesis of compatible solutes. This large-scale expression dataset of drought-induced CAM demonstrates transcriptional regulation of the C3-CAM transition. We identified candidate transcription factors to mediate this photosynthetic plasticity, which may contribute in the future to the design of more drought-tolerant crops via engineered CAM. PMID:26530316
Winter, Klaus
2016-01-01
Drought tolerance is a key factor for agriculture in the 21st century as it is a major determinant of plant survival in natural ecosystems as well as crop productivity. Plants have evolved a range of mechanisms to cope with drought, including a specialized type of photosynthesis termed Crassulacean acid metabolism (CAM). CAM is associated with stomatal closure during the day as atmospheric CO2 is assimilated primarily during the night, thus reducing transpirational water loss. The tropical herbaceous perennial species Talinum triangulare is capable of transitioning, in a facultative, reversible manner, from C3 photosynthesis to weakly expressed CAM in response to drought stress. The transcriptional regulation of this transition has been studied. Combining mRNA-Seq with targeted metabolite measurements, we found highly elevated levels of CAM-cycle enzyme transcripts and their metabolic products in T. triangulare leaves upon water deprivation. The carbohydrate metabolism is rewired to reduce the use of reserves for growth to support the CAM-cycle and the synthesis of compatible solutes. This large-scale expression dataset of drought-induced CAM demonstrates transcriptional regulation of the C3–CAM transition. We identified candidate transcription factors to mediate this photosynthetic plasticity, which may contribute in the future to the design of more drought-tolerant crops via engineered CAM. PMID:26530316
Multirresolución adaptativa de mallas triangulares basado en criterios de textura
Directory of Open Access Journals (Sweden)
Alexánder Ceballos
2007-01-01
Full Text Available Los modelos 3D están generalmente compuestos por miles de polígonos. En ocasiones estas representaciones pueden obtenerse con la misma calidad visual pero con un menor número de polígonos. En este artículo se propone un método para reducir el tamaño de imágenes 3D texturadas basadas en mallas triangulares, conservando la calidad visual del modelo. Se introduce un criterio de textura que controla el proceso de decimación triangular. Para eliminar puntos sin necesidad de realizar una nueva triangulación, sobre la nube de puntos se usa un algoritmo poligonal de decimación. Para definir cuáles puntos deben ser removidos, se usa un filtro de Sobel 2D sobre la textura correspondiente. Se muestra que se puede usar el algoritmo para reducir los tiempos de carga, de renderización, de transferencia y de almacenamiento de una imagen 3D texturada
Spontaneous formation of kagome network and Dirac half-semimetal on a triangular lattice
Akagi, Yutaka; Motome, Yukitoshi
2015-04-01
In spin-charge coupled systems, geometrical frustration of underlying lattice structures can give rise to nontrivial magnetic orders and electronic states. Here we explore such a possibility in the Kondo lattice model with classical localized spins on a triangular lattice by using a variational calculation and simulated annealing. We find that the system exhibits a four-sublattice collinear ferrimagnetic phase at 5/8 filling for a large Hund's-rule coupling. In this state, the system spontaneously differentiates into the up-spin kagome network and the isolated down-spin sites, which we call the kagome network formation. In the kagome network state, the system becomes Dirac half-semimetallic: The electronic structure shows a massless Dirac node at the Fermi level, and the Dirac electrons are almost fully spin polarized due to the large Hund's-rule coupling. We also study the effect of off-site Coulomb repulsion in the kagome network phase where the system is effectively regarded as a 1/3-filling spinless fermion system on the kagome lattice. We find that, at the level of the mean-field approximation, a √{3 }×√{3 } -type charge order occurs in the kagome network state, implying the possibility of fractional charge excitations in this triangular lattice system. Moreover, we demonstrate that the kagome network formation with fully polarized Dirac electrons are controllable by an external magnetic field.
Effects of thin fin on natural convection in porous triangular enclosures
Energy Technology Data Exchange (ETDEWEB)
Varol, Yasin [Department of Mechanical Engineering, Vanderbilt University, Nashville, TN 37235 (United States); Oztop, Hakan F. [Department of Mechanical Engineering, Firat University, TR-23119, Elazig (Turkey); Varol, Asaf [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26505 (United States)
2007-10-15
A two-dimensional solution of natural convection in solid adiabatic thin fin attached to porous right triangular enclosures has been analyzed numerically. The vertical wall of the enclosure is insulated while the bottom and the inclined walls are isothermal. The temperature of the bottom wall is higher than the temperature of the inclined wall. Governing equations, which are written using Darcy model, are solved via the finite difference technique. The Successive Under Relaxation (SUR) method was used to solve linear algebraic equations. Dimensionless location of the thin fin from 0.2 to 0.6, the aspect ratio of triangular enclosure from 0.25 to 1, Rayleigh number from 100 to 1000 and the dimensionless height of the fin from 0.1 to 0.4 are used as governing parameters that are effective on heat transfer and fluid flow. Results for the mean Nusselt number, velocity profiles, the contour maps of the streamlines and isotherms are presented. It is observed that the thin fin can be used as a passive control element for flow field, temperature distribution and heat transfer. (author)
Kaporin, I. E.
2012-02-01
In order to precondition a sparse symmetric positive definite matrix, its approximate inverse is examined, which is represented as the product of two sparse mutually adjoint triangular matrices. In this way, the solution of the corresponding system of linear algebraic equations (SLAE) by applying the preconditioned conjugate gradient method (CGM) is reduced to performing only elementary vector operations and calculating sparse matrix-vector products. A method for constructing the above preconditioner is described and analyzed. The triangular factor has a fixed sparsity pattern and is optimal in the sense that the preconditioned matrix has a minimum K-condition number. The use of polynomial preconditioning based on Chebyshev polynomials makes it possible to considerably reduce the amount of scalar product operations (at the cost of an insignificant increase in the total number of arithmetic operations). The possibility of an efficient massively parallel implementation of the resulting method for solving SLAEs is discussed. For a sequential version of this method, the results obtained by solving 56 test problems from the Florida sparse matrix collection (which are large-scale and ill-conditioned) are presented. These results show that the method is highly reliable and has low computational costs.
Time detector design for MeV particles. I. The electric field in a triangular domain
International Nuclear Information System (INIS)
We describe in this paper the methods used in the calculation of the electric potential and field in a triangular domain. These calculations are needed in the design of a time detector for high-energy particles. The electric field is created by three metal plates forming a triangular prism with different voltage applied to each of the plates. An analytical solution to the electric potential and field within the triangle is introduced. The method is based on the conformal mapping principle. The discovery of the analytical mapping functions which convert a triangle to a parallel band is of key importance to the solution. Although the methods described in this paper are given for right angled isosceles triangle, which is used in the time detector design, the method is in fact applicable to any triangles. The same problem has also been solved using the standard numerical method in which the electric potential is calculated on a set of grid points. The accuracy of the numerical solution depends on the size of the grid and the precision of iteration, which are generally limited by the computing resources. In comparison with the numerical method the analytical solution yields required information in a much more efficient and accurate way. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Martínez-Orozco, J.C. [Unidad Académica de Física. Universidad Autónoma de Zacatecas, Calzada Solidaridad esquina con Paseo la Bufa S/N, C.P. 98060. Zacatecas, Zac. (Mexico); Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Duque, C.A., E-mail: cduque@fisica.udea.edu.co [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)
2014-11-01
The conduction band states of GaAs-based vertically coupled double triangular quantum dots in two dimensions are investigated within the effective mass and parabolic approximation, using a diagonalization procedure to solve the corresponding Schrödinger-like equation. The effect of an externally applied static electric field is included in the calculation, and the variation of the lowest confined energy levels as a result of the change of the field strength is reported for different geometrical setups. The linear and nonlinear optical absorptions and the relative change of the refractive index, associated with the energy transition between the ground and the first excited state in the system, are studied as a function of the incident light frequency for distinct configurations of inter-dot distance and electric field intensities. The blueshift of the resonant absorption peaks is detected as a consequence of the increment in the field intensity, whereas the opposite effect is obtained from the increase of inter-dot vertical distance. It is also shown that for large enough values of the electric field there is a quenching of the optical absorption due to field-induced change of symmetry of the first excited state wavefunction, in the case of triangular dots of equal shape and size.
Zeinali Heris, Saeed; Noie, Seyyed Hossein; Talaii, Elham; Sargolzaei, Javad
2011-02-28
In this article, laminar flow-forced convective heat transfer of Al2O3/water nanofluid in a triangular duct under constant wall temperature condition is investigated numerically. In this investigation, the effects of parameters, such as nanoparticles diameter, concentration, and Reynolds number on the enhancement of nanofluids heat transfer is studied. Besides, the comparison between nanofluid and pure fluid heat transfer is achieved in this article. Sometimes, because of pressure drop limitations, the need for non-circular ducts arises in many heat transfer applications. The low heat transfer rate of non-circular ducts is one the limitations of these systems, and utilization of nanofluid instead of pure fluid because of its potential to increase heat transfer of system can compensate this problem. In this article, for considering the presence of nanoparticl: es, the dispersion model is used. Numerical results represent an enhancement of heat transfer of fluid associated with changing to the suspension of nanometer-sized particles in the triangular duct. The results of the present model indicate that the nanofluid Nusselt number increases with increasing concentration of nanoparticles and decreasing diameter. Also, the enhancement of the fluid heat transfer becomes better at high Re in laminar flow with the addition of nanoparticles.
Directory of Open Access Journals (Sweden)
Borovský Michal
2016-01-01
Full Text Available The population annealing algorithm is a novel approach to study systems with rough free-energy landscapes, such as spin glasses. It combines the power of simulated annealing, Boltzmann weighted differential reproduction and sequential Monte Carlo process to bring the population of replicas to the equilibrium even in the low-temperature region. Moreover, it provides a very good estimate of the free energy. The fact that population annealing algorithm is performed over a large number of replicas with many spin updates, makes it a good candidate for massive parallelism. We chose the GPU programming using a CUDA implementation to create a highly optimized simulation. It has been previously shown for the frustrated Ising antiferromagnet on the stacked triangular lattice with a ferromagnetic interlayer coupling, that standard Markov Chain Monte Carlo simulations fail to equilibrate at low temperatures due to the effect of kinetic freezing of the ferromagnetically ordered chains. We applied the population annealing to study the case with the isotropic intra- and interlayer antiferromagnetic coupling (J2/|J1| = −1. The reached ground states correspond to non-magnetic degenerate states, where chains are antiferromagnetically ordered, but there is no long-range ordering between them, which is analogical with Wannier phase of the 2D triangular Ising antiferromagnet.
Xu, Shanzhi; Wang, Peng; Dong, Yonggui
2016-01-01
In order to measure the impedance variation process in electrolyte solutions, a method of triangular waveform voltage excitation is investigated together with principal component analysis (PCA). Using triangular waveform voltage as the excitation signal, the response current during one duty cycle is sampled to construct a measurement vector. The measurement matrix is then constructed by the measurement vectors obtained from different measurements. After being processed by PCA, the changing information of solution impedance is contained in the loading vectors while the response current and noise information is contained in the score vectors. The measurement results of impedance variation by the proposed signal processing method are independent of the equivalent impedance model. The noise-induced problems encountered during equivalent impedance calculation are therefore avoided, and the real-time variation information of noise in the electrode-electrolyte interface can be extracted at the same time. Planar-interdigitated electrodes are experimentally tested for monitoring the KCl concentration variation process. Experimental results indicate that the measured impedance variation curve reflects the changing process of solution conductivity, and the amplitude distribution of the noise during one duty cycle can be utilized to analyze the contact conditions of the electrode and electrolyte interface. PMID:27110787
Linear analysis of a backward wave oscillator with triangular corrugated slow wave structure
Saber, Md. Ghulam; Sagor, Rakibul Hasan; Amin, Md. Ruhul
2016-05-01
In this work, a backward wave oscillator (BWO) with triangularly corrugated periodic metallic slow wave structure (TrCSWS) driven by an infinitely thin annular electron beam is studied using linear theory. The electron beam is assumed to be guided by a strong magnetic field. The triangular axial profile of the SWS is approximated by a Fourier series in order to apply the linear Rayleigh-Fourier (R-F) theory that has long been used in the theoretical analysis of BWOs with sinusoidally corrugated SWS (SCSWS). The dispersion equation for various beam parameters has been solved and the temporal growth rate (TGR) of the electromagnetic wave for the fundamental TM_{01} mode is calculated numerically. The TGR values for different beam parameters have been compared with those of the BWO with SCSWS, semi-circularly corrugated SWS (SCCSWS) and trapezoidally corrugated SWS (TCSWS). In order to compare the TGR values, the amplitude of corrugation of the TrCSWS is varied so that its dispersion curve of TM_{01} mode almost coincides with that of the SCSWS and TCSWS. The study reveals that the performance (in terms of TGR) of the proposed BWO with TrCSWS is comparable to that of other BWOs with SCSWS and TCSWS for the same set of beam parameters and it provides significantly better performance than SCCSWS. So, the proposed TrCSWS that can easily be constructed may replace SCSWS, SCCSWS or TCSWS as their viable alternative.
Directory of Open Access Journals (Sweden)
Zeinali Heris Saeed
2011-01-01
Full Text Available Abstract In this article, laminar flow-forced convective heat transfer of Al2O3/water nanofluid in a triangular duct under constant wall temperature condition is investigated numerically. In this investigation, the effects of parameters, such as nanoparticles diameter, concentration, and Reynolds number on the enhancement of nanofluids heat transfer is studied. Besides, the comparison between nanofluid and pure fluid heat transfer is achieved in this article. Sometimes, because of pressure drop limitations, the need for non-circular ducts arises in many heat transfer applications. The low heat transfer rate of non-circular ducts is one the limitations of these systems, and utilization of nanofluid instead of pure fluid because of its potential to increase heat transfer of system can compensate this problem. In this article, for considering the presence of nanoparticl: es, the dispersion model is used. Numerical results represent an enhancement of heat transfer of fluid associated with changing to the suspension of nanometer-sized particles in the triangular duct. The results of the present model indicate that the nanofluid Nusselt number increases with increasing concentration of nanoparticles and decreasing diameter. Also, the enhancement of the fluid heat transfer becomes better at high Re in laminar flow with the addition of nanoparticles.
基于Wiener指数的极值三角链%On the Wiener index of triangular chains
Institute of Scientific and Technical Information of China (English)
温长昆; 任海珍
2013-01-01
图G的Wiener指数定义为图G中所有点对的距离和.讨论了空间三角链关于Wiener指数的极值问题,证明了线性三角链和螺旋三角链分别达到最大的Wiener指数和最小的Wiener指数.%The Wiener index of the graph G is defined as the sum over all unordered pairs of distinct vertices in G. The Wiener index of geometrically planar triangular chains is characterized. It is showed that the linear triangular chain and helicene triangular chain attain the maximum Wiener index and minimum Wiener index, respectively.
Guiding 2.94 μm using low-loss microstructured antiresonant triangular-core fibers
Chen, Yang; Saleh, Mohammed F.; Joly, Nicolas Y.; Biancalana, Fabio
2016-04-01
We introduce a new simple design of hollow-core microstructured fiber targeted to guide mid-infrared light at a wavelength of 2.94 μm. The fiber has a triangular-core supported via silica-glass webs enclosed by a large hollow capillary tube. The fiber specific dimensions are determined by the anti-resonant guiding mechanism. For a triangular-core with side length 100 μm, the fiber has a minimum transmission loss 0.08 ± 0.005 dB/m and dispersion 2.3 ps/km/nm at the operational wavelength of 2.94 μm.
弱可约极大三角代数的上同调%Cohomology of Weakly Reducible Maximal Triangular Algebras
Institute of Scientific and Technical Information of China (English)
董浙; 鲁世杰
2000-01-01
In this paper, we introduce the concept of weakly reducible maximal triangular algebras which form a large class of maximal triangular algebras. Let (ж)be a wakly closed algebra containing (ж) , we prove that the cohomulogy spaces Hn((y).(ж) ) (n≥1) are trivial.
High-speed ground moving target detection research using triangular modulation FMCW
Institute of Scientific and Technical Information of China (English)
Yi LIANG; Long ZHANG; Mengdao XING; Zheng BAO
2009-01-01
The frequency modulated continuous wave (FMCW) radar has the characteristics of low probability of interception, good hidden property and the ability to counter anti-radiation missiles. This paper proposes a new method for high-speed ground moving target detection (GMTD) using triangular modulation FMCW. According to the characteristic of the opposite range shift induced by the upslope and downslope modulation FMCW, the upslope and downslope are imaged, respectively. After compensation of continuous motion of the platform and time difference between upslope and downslope signals for imaging, the moving target can be detected through displaced phase center antenna (DPCA) technology.When the moving target is detected, the moving target image is extracted, and correlation processing is used to obtain the range shift, which can be used to estimate the target radial velocity, and further to find the real position of the target. The effectiveness of this method is verified by the result of computer simulation.
Ultrathin dendritic Pt3Cu triangular pyramid caps with enhanced electrocatalytic activity.
Kuang, Yun; Cai, Zhao; Zhang, Ying; He, Dongsheng; Yan, Xiuling; Bi, Yongmin; Li, Yaping; Li, Ziyou; Sun, Xiaoming
2014-10-22
Here we report on the synthesis of novel dendritic Pt3Cu triangular pyramid caps via a solvothermal coreduction method. These caps had three-dimensional caved structures with ultrathin branches, as evidenced by high-resolution transmission electron microscopy (HRTEM) and HAADF-STEM characterization. Tuning the reduction kinetics of two metal precursors by an iodide ion was believed to be the key for the formation of an alloyed nanostructure. Electro-oxidation of methanol and formic acid showed dramatically improved electrocatalytic activities and poison-tolerance for these nanoalloys as compared to commercial Pt/C catalysts, which was attributed to their unique open porous structure with interconnected network, ultrahigh surface areas, as well as synergetic effect of the two metallic components.
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Sakshi Gupta
2015-12-01
Full Text Available In this paper, application of fuzzy logic technique using triangular membership function for developing models for predicting compressive strength of concrete with partial replacement of cement with nanosilica has been carried out. For this, the data have been taken from various literatures and help in optimizing the constituents available and reducing cost and efforts in studying design to develop mixes by predefining suitable range for experimenting. The use of nanostructured materials in concrete can add many benefits that are directly related to the durability of various cementitious materials, besides the fact that it is possible to reduce the quantities of cement in the composite. Successful prediction by the model indicates that fuzzy logic could be a useful modelling tool for engineers and research scientists in the area of cement and concrete. Compressive strength values of concrete can be predicted in fuzzy logic models without attempting any experiments in a quite short period of time with tiny error rates.
Kumar, Anil; Mabon, James C; Chow, Edmond; Fang, Nicholas X
2010-01-01
Cathodoluminescence (CL) imaging spectroscopy is an important technique to understand resonant behavior of optical nanoantennas. We report high-resolution CL spectroscopy of triangular gold nanoantennas designed with near-vacuum effective index and very small metal-substrate interface. This design helped in addressing issues related to background luminescence and shifting of dipole modes beyond visible spectrum. Spatial and spectral investigations of various plasmonic modes are reported. Out-of-plane dipole modes excited with vertically illuminated electron beam showed high-contrast tip illumination in panchromatic imaging. By tilting the nanostructures during fabrication, in-plane dipole modes of antennas were excited. Finite-difference time-domain simulations for electron and optical excitations of different modes showed excellent agreement with experimental results. Our approach of efficiently exciting antenna modes by using low index substrates is confirmed both with experiments and numerical simulations....
Localized surface plasmons in face to face dimer silver triangular prism nanoparticles
Azarian, Abas; Babaei, Ferydon
2016-05-01
Using the discrete dipole approximation method, all plasmonic bands in 80 nm silver face to face dimer triangular prism nanoparticles were reported. The characteristics of plasmonics peaks were investigated with variations of dimer gap and refractive index of the surrounding medium of dimer. We found that there are three and four plasmonic bands, respectively, for dimer separation 2 and 4 nm. The extinction spectra and electric field distribution showed that the dipole-dipole interaction creates strong plasmonic band, but the quadrupole-quadrupole interaction relates to weak plasmonic band. The results revealed that the strong plasmonic bands have high sensitivity factors with respect to weak plasmonic bands. This study may be used in the synthesis of asymmetric dimers made of metal nanoparticles with new plasmonics properties.
Sobre relaciones laborales triangulares: La subcontratación y el suministro de trabajadores
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José Luis Ugarte Cataldo
2006-01-01
Full Text Available Las relaciones laborales triangulares puede adoptar, en lo fundamental, dos modalidades: la subcontratación laboral y el suministro de trabajadores por la vía de una empresa de trabajo temporal. La primera se refiere a la situación en que una empresa, dueña de una obra o faena, contrata a otra empresa, denominada contratista, mediante un contrato civil o comercial, para que ejecute a su cuenta y riesgo, con sus propios trabajadores, un determinado trabajo o servicio, pudiendo esta última a su turno, contratar a otra empresa, denominada subcontratista, para que lleve a cabo el trabajo o servicio requerido. La segunda, en cambio, consiste en que una empresa, cuyo giro corresponde al suministro de trabajadores (empresa suministradora o de trabajo temporal, pone a disposición de otra empresa (denominada usuaria, por el pago de un precio determinado, los servicios laborales de sus empleados, reteniendo para sí la calidad formal de empleador. En Chile, mientras la figura de la subcontratación laboral data de antiguo, y está regulada en la legislación vigente, el caso del suministro es distinto: sólo en los últimos años se presenta como un fenómeno de relevancia para la comunidad jurídica nacional, en directa relación con el momento de moda que vive la denominada descentralización productiva, que no se encuentra, por lo demás, reconocida en nuestra legislación laboral. La regulación de ambos tipos de relaciones triangulares es el objetivo al que va a la dirigido nueva ley de subcontratación: por una parte, se reconoce y regula por primera vez en Chile la figura del suministro de personal a través de lo que denomina empresas de servicios transitorios, y se perfecciona, por otra, la regulación de la subcontratación laboral mediante nuevas normas sobre la responsabilidad del dueño de la obraThe triangular labour relations could basically adopt two modalities: labour subcontracting and the supplying of workers by a temporary
International Nuclear Information System (INIS)
A scalable approach for integrated photonic networks in single-crystal diamond using triangular etching of bulk samples is presented. We describe designs of high quality factor (Q = 2.51 × 106) photonic crystal cavities with low mode volume (Vm = 1.062 × (λ/n)3), which are connected via waveguides supported by suspension structures with predicted transmission loss of only 0.05 dB. We demonstrate the fabrication of these structures using transferred single-crystal silicon hard masks and angular dry etching, yielding photonic crystal cavities in the visible spectrum with measured quality factors in excess of Q = 3 × 103
A Finite Volume Method with Unstructured Triangular Grids for Numerical Modeling of Tidal Current
Institute of Scientific and Technical Information of China (English)
SHI Hong-da; LIU zhen
2005-01-01
The finite volume method (FVM) has many advantages in 2-D shallow water numerical simulation. In this study, the finite volume method is used with unstructured triangular grids to simulate the tidal currents. The Roe scheme is applied in the calculation of the intercell numerical flux, and the MUSCL method is introduced to improve its accuracy. The time integral is a two-step scheme of forecast and revision. For the verification of the present method, the Stoker's problem is calculated and the result is compared with the mathematically analytic solutions. The comparison indicates that the method is feasible. A sea area of a port is used as an example to test the method established here. The result shows that the present computational method is satisfactory, and it could be applied to the engineering fields.
Elliptic and Triangular Flow of Identified Particles from the AMPT Model at RHIC Energies
Sun, Xu; Schmah, Alexander; Shi, Shusu; Zhang, Jingbo; Huo, Lei; Jiang, Hanzhi
2015-01-01
The elliptic flow ($v_{2}$) at $\\sqrt{s_{\\rm NN}} = $ 11.5, 39, and 200 GeV and triangular flow ($v_{3}$) at $\\sqrt{s_{\\rm NN}} = $ 200 GeV of identified particles ($\\pi^{\\pm}, K^{\\pm}, K^{0}_{S}, p, \\bar{p}, \\phi, \\Lambda$ and $\\bar{\\Lambda}$) from 0\\%--80\\% central Au+Au collisions are analyzed using a multiphase transport (AMPT) model. It is shown that the experimental results from the $\\eta$-sub event plane method can be reproduced with a parton scattering cross section between 1.5 and 3 mb. We also studied the differential and integrated $v_{2}/v_{3}$ ratios and conclude that they are anti-corrected with the parton scattering cross section.
Enhanced photocatalysis by coupling of anatase TiO2 film to triangular Ag nanoparticle island.
Xu, Jinxia; Xiao, Xiangheng; Ren, Feng; Wu, Wei; Dai, Zhigao; Cai, Guangxu; Zhang, Shaofeng; Zhou, Juan; Mei, Fei; Jiang, Changzhong
2012-01-01
In order to overcome the low utilization ratio of solar light and high electron-hole pair recombination rate of TiO2, the triangular Ag nanoparticle island is covered on the surface of the TiO2 thin film. Enhancement of the photocatalytic activity of the Ag/TiO2 nanocomposite system is observed. The increase of electron-hole pair generation is caused by the enhanced near-field amplitudes of localized surface plasmon of the Ag nanoparticles. The efficiently suppressed recombination of electron-hole pair caused by the metal-semiconductor contact can also enhance the photocatalytic activity of the TiO2 film. PMID:22548875
Study of energy eigenvalues and density of states of carriers in a triangular quantum wire
Deyasi, Arpan; Bhattacharyya, S.; Das, N. R.
2012-10-01
Energy eigenvalues and density of states of carriers in a finite barrier triangular quantum wire embedded inside a rectangular quantum wire are numerically investigated using finite difference technique (FD-Q). Time-independent Schrödinger's equation is solved with appropriate boundary conditions for computation of lowest three eigenstates. The wire is made of lower bandgap GaAs material surrounded by wider bandgap AlxGa1-xAs, and the analysis is carried out by taking into consideration of the conduction band discontinuity and effective mass mismatch at the boundaries. The eigenvalues and the density of states are plotted as function of wire dimension and mole fraction (x). The results are also compared with those obtained using rectangular quantum wire.
Parametric investigation of boundary layer control using triangular micro vortex generators
Bagheri, Milad; Muslmani, Motassem Al; Masood, Asad; Khosravi, Mahmood; Atef Mahmoud, Mohamed; Cardoz, Aniket; Akkuwari, Abdulrahman; Alanezi, Yusuf; Kim, Young
2014-03-01
Improving the aerodynamic performance of an airfoil is one of the primary interests of the Aerodynamicists. Such performance improvement can be achieved using passive or active flow control devices. One of such passive devices having a compact size along with an effective performance is the Micro Vortex Generators (MVGs). A special type of MVGs, which has been recently introduced in the aerospace industry, is "Triangular Shape" MVGs and its impact on aerodynamic characteristics is the main interest of this study. This study will compare the effects of various configurations through which delay of the flow separation using boundary layer control will be analysed by experimental and theoretical approach. The experimental investigations have been conducted using subsonic wind tunnel and the theoretical analysis using ANSYS® 13.0 FLUENT of which the final results are compared with each other.
Parametric investigation of boundary layer control using triangular micro vortex generators
Directory of Open Access Journals (Sweden)
Bagheri Milad
2014-03-01
Full Text Available Improving the aerodynamic performance of an airfoil is one of the primary interests of the Aerodynamicists. Such performance improvement can be achieved using passive or active flow control devices. One of such passive devices having a compact size along with an effective performance is the Micro Vortex Generators (MVGs. A special type of MVGs, which has been recently introduced in the aerospace industry, is “Triangular Shape” MVGs and its impact on aerodynamic characteristics is the main interest of this study. This study will compare the effects of various configurations through which delay of the flow separation using boundary layer control will be analysed by experimental and theoretical approach. The experimental investigations have been conducted using subsonic wind tunnel and the theoretical analysis using ANSYS® 13.0 FLUENT of which the final results are compared with each other.
SFM-FDTD analysis of triangular-lattice AAA structure: Parametric study of the TEM mode
Hamidi, M.; Chemrouk, C.; Belkhir, A.; Kebci, Z.; Ndao, A.; Lamrous, O.; Baida, F. I.
2014-05-01
This theoretical work reports a parametric study of enhanced transmission through annular aperture array (AAA) structure arranged in a triangular lattice. The effect of the incidence angle in addition to the inner and outer radii values on the evolution of the transmission spectra is carried out. To this end, a 3D Finite-Difference Time-Domain code based on the Split Field Method (SFM) is used to calculate the spectral response of the structure for any angle of incidence. In order to work through an orthogonal unit cell which presents the advantage to reduce time and space of computation, special periodic boundary conditions are implemented. This study provides a new modeling of AAA structures useful for producing tunable ultra-compact devices.
Novel FBG triangular filter for interrogating a FBG sensor in dynamic strain measurement
Institute of Scientific and Technical Information of China (English)
SHAO Li-yang; SONG Jian-fei; ZHANG A-ping; HE Sai-ling
2006-01-01
@@ We demonstrate the fabrication and the application of an in-fiber triangular filter (T-filter) based on a linearly chirped and apodized fiber Bragg grating (FBG).The theoretical analysis shows that this type of FBG T-filter has a good response in the demodulation of a wavelength-matched FBG sensor.For the first time to our knowledge,such an FBG T-filter has been realized in our laboratory,and utilized to interrogate the signal of dynamic strain by a specially designed measurement scheme.Experimental results have proved that the system has a good performance in the measurement of dynamic strain.Because of its compactness and passiveness,such type of the device can be integrated as a portable demodulation module.
Radial Basis Function Based Implicit Surface Reconstruction Interpolating Arbitrary Triangular Mesh
Institute of Scientific and Technical Information of China (English)
PANG Mingyong
2006-01-01
In this paper, we present an approach for smooth surface reconstructions interpolating triangular meshes with arbitrary topology and geometry. The approach is based on the well-known radial basis functions (RBFs) and the constructed surfaces are generalized thin-plate spline surfaces. Our algorithm first defines a pair of offset points for each vertex of a given mesh to enhance the controllability of local geometry and to assure stability of the construction. A linear system is then solved by LU decomposition and the implicit governing equation of interpolating surface is obtained. The constructed surfaces finally are visualized by a Marching Cubes based polygonizer. The approach provides a robust and efficient solution for smooth surface reconstruction from various 3D meshes.
Application of the control volume mixed finite element method to a triangular discretization
Naff, R.L.
2012-01-01
A two-dimensional control volume mixed finite element method is applied to the elliptic equation. Discretization of the computational domain is based in triangular elements. Shape functions and test functions are formulated on the basis of an equilateral reference triangle with unit edges. A pressure support based on the linear interpolation of elemental edge pressures is used in this formulation. Comparisons are made between results from the standard mixed finite element method and this control volume mixed finite element method. Published 2011. This article is a US Government work and is in the public domain in the USA. ?? 2012 John Wiley & Sons, Ltd. This article is a US Government work and is in the public domain in the USA.
Unusual Charge Transport and Spin Response of Doped Bilayer Triangular Antiferromagnets
Institute of Scientific and Technical Information of China (English)
LIANG Ying; MA Tian-Xing; FENG Shi-Ping
2003-01-01
Within the t-J model, the charge transport and spin response of the doped bilayer triangular antiferromagnetare studied by considering the bilayer interaction. Although the bilayer interaction leads to the band splitting in theelectronic structure, the qualitative behaviors of the physical properties are the same as in the single layer case. Theconductivity spectrum shows the low-energy peak and unusual midinfrared band, the temperature-dependent resistivityis characterized by the nonlinearity metallic-like behavior in the higher temperature range and the deviation from themetallic-like behavior in the lower temperature range and the commensurate neutron scattering peak near the half-fillingis split into six incommensurate peaks in the underdoped regime, with the incommensurability increasing with the holeconcentration at lower dopings, and saturating at higher dopings.
Fitting polynomial surfaces to triangular meshes with Voronoi Squared Distance Minimization
Nivoliers, Vincent
2011-12-01
This paper introduces Voronoi Squared Distance Minimization (VSDM), an algorithm that fits a surface to an input mesh. VSDM minimizes an objective function that corresponds to a Voronoi-based approximation of the overall squared distance function between the surface and the input mesh (SDM). This objective function is a generalization of Centroidal Voronoi Tesselation (CVT), and can be minimized by a quasi-Newton solver. VSDM naturally adapts the orientation of the mesh to best approximate the input, without estimating any differential quantities. Therefore it can be applied to triangle soups or surfaces with degenerate triangles, topological noise and sharp features. Applications of fitting quad meshes and polynomial surfaces to input triangular meshes are demonstrated.
Fitting polynomial surfaces to triangular meshes with Voronoi squared distance minimization
Nivoliers, Vincent
2012-11-06
This paper introduces Voronoi squared distance minimization (VSDM), an algorithm that fits a surface to an input mesh. VSDM minimizes an objective function that corresponds to a Voronoi-based approximation of the overall squared distance function between the surface and the input mesh (SDM). This objective function is a generalization of the one minimized by centroidal Voronoi tessellation, and can be minimized by a quasi-Newton solver. VSDM naturally adapts the orientation of the mesh elements to best approximate the input, without estimating any differential quantities. Therefore, it can be applied to triangle soups or surfaces with degenerate triangles, topological noise and sharp features. Applications of fitting quad meshes and polynomial surfaces to input triangular meshes are demonstrated. © 2012 Springer-Verlag London.
International Nuclear Information System (INIS)
The inverse radiation analysis of a two-dimensional irregular configuration using unstructured triangular meshes is presented. In this study, an enclosure filled with an absorbing, emitting and scattering medium with diffusely emitting and reflecting opaque boundaries is considered. The finite volume method is applied to solve the radiative transfer equation in order to simulate the measured incident radiation values which are used as input data for the inverse analysis. The conjugate gradient method is adopted for the estimation of wall emissivities by minimizing the objective function at each iteration step. To verify the performance of the unstructured grid system, we compare the results with those using a structured grid system for the two-dimensional lopsided shape. The effect of measurement errors on the estimation accuracy is also investigated
Oguri, Akira; Amaha, Shinichi; Nisikawa, Yunori; Hewson, A. C.; Tarucha, Seigo; Numata, Takahide
2010-03-01
We study transport through a triangular triple quantum dot (TTQD) connected to two noninteracting leads, using the numerical renormalization group. The system has been theoretically revealed to show a variety of Kondo effects depending on the electron filling of the triangle [1]. For instance, the SU(4) Kondo effect takes place at three-electron filling, and a two-stage Kondo screening of a high-spin S=1 Nagaoka state takes place at four-electron filling. Because of the enhanced freedom in the configurations, however, the large parameter space of the TTQD still has not been fully explored, especially for large deformations. We report the effects of the inhomogeneity in the inter-dot couplings and the level positions in a wide region of the filling. [1] T. Numata, Y. Nisikawa, A. Oguri, and A. C. Hewson: PRB 80, 155330 (2009).
Nataf, Pierre; Lajkó, Miklós; Wietek, Alexander; Penc, Karlo; Mila, Frédéric; Läuchli, Andreas M.
2016-10-01
We show that, in the presence of a π /2 artificial gauge field per plaquette, Mott insulating phases of ultracold fermions with SU (N ) symmetry and one particle per site generically possess an extended chiral phase with intrinsic topological order characterized by an approximate ground space of N low-lying singlets for periodic boundary conditions, and by chiral edge states described by the SU(N ) 1 Wess-Zumino-Novikov-Witten conformal field theory for open boundary conditions. This has been achieved by extensive exact diagonalizations for N between 3 and 9, and by a parton construction based on a set of N Gutzwiller projected fermionic wave functions with flux π /N per triangular plaquette. Experimental implications are briefly discussed.
From Discreteness to Continuity: Dislocation Equation for Two-Dimensional Triangular Lattice
Institute of Scientific and Technical Information of China (English)
WANG Shao-Feng
2007-01-01
@@ A systematic method from the discreteness to the continuity is presented for the dislocation equation of the triangular lattice. A modification of the Peierls equation has been derived strictly. The modified equation includes the higher order corrections of the discrete effect which are important for the core structure of dislocation. It is observed that the modified equation possesses a universal form which is model-independent except the factors.The factors, which depend on the detail of the model, are related to the derivatives of the kernel at its zero point in the wave-vector space. The results open a way to deal with the complicated models because what one needs to do is to investigate the behaviour near the zero point of the kernel in the wave-vector space instead of calculating the kernel completely.
An improvement of the lattice theory of dislocation for a two-dimensional triangular crystal
Institute of Scientific and Technical Information of China (English)
Wang Shao-Feng
2005-01-01
The structure of dislocation in a two-dimensional triangular crystal has been studied theoretically on the basis of atomic interaction and lattice statics. The theory presented in this paper is an improvement to that published previously.Within a reasonable interaction approximation, a new dislocation equation is obtained, which remedies a fault existing in the lattice theory of dislocation. A better simplification of non-diagonal terms of the kernel is given. The solution of the new dislocation equation asymptotically becomes the same as that obtained in the elastic theory, and agrees with experimental data. It is found that the solution is formally identical with that proposed phenomenologically by Foreman et al, where the parameter can be chosen freely, but cannot uniquely determined from theory. Indeed, if the parameter in the expression of the solution is selected suitably, the expression can be well applied to describe the fine structure of the dislocation.
Fabrication of a label-free plasmon immunosensor based on triangular silver nanoplates
Dong, Peipei; Lin, Yuanyuan; Di, Junwei
2013-08-01
In this work, we have firstly electrodeposited small gold seeds (average diameter of ~40 nm) onto transparent indium tin oxide (ITO) thin film coated glass. Then silver triangular nanoplates with edge lengths of ~200 nm were fabricated using seed-mediated growth method. The localized surface plasmon resonance (LSPR) peak was located at ~700 nm. Finally, a label-free plasmon immunosensor was prepared by directly immobilizing goat anti-mouse IgG onto silver surface. The performance of the LSPR immunosensor was investigated. The red-shift of the biosensor was linearly proportional to mouse IgG concentration ranged from 5 ng/mL to 500 ng/mL, with a detection limit of 2 ng/mL. The label-free immunosensor was simple, sensitive and selective.
A Revision Restoring Projection after Nipple Reconstruction by Burying Four Triangular Dermal Flaps
Kim, Ji Hun
2016-01-01
Background Numerous techniques have been used to achieve long-term projection of the nipple following nipple-areola reconstruction. However, the reconstructed nipple loses projection over time. We describe a technique that uses local flaps to improve the lost projection of reconstructed nipples. Methods Between November 2013 and March 2015, nine patients (11 nipples) underwent revisional nipple reconstruction for lost projection. Only C–H nipple reconstructions were included in this study. The medical history of each patient was reviewed and photographs were taken in front and lateral views. All patients attended routine follow-up visits. Deepithelialized triangular flaps were made on all four sides of the nipple and buried in the opposite corners in order to augment the volume of the nipple. Anchoring sutures were used to attach each triangular flap on the side opposite their point of origin, and the resulting defects were closed directly. Results This procedure was used successfully in nine patients (11 nipples). Adequate projection was achieved in all patients and no complications occurred. The average nipple height was 3 mm before operation, 7 mm one day after operation, 5 mm at the six-month follow-up, and 5 mm at the 12-month follow-up. The average nipple-areolar angle was 164° before the operation, 111° one day after the operation, 130° at the six-month follow-up, and 133° at the 12-month follow-up. Conclusions The method described provides a solution to the loss of projection in reconstructed nipples. We recommend this technique because it leads to better projection, greater volume, and a more natural shape.
Kondo effects in a triangular triple quantum dot with lower symmetries
Oguri, A.; Amaha, S.; Nishikawa, Y.; Numata, T.; Shimamoto, M.; Hewson, A. C.; Tarucha, S.
2011-05-01
We study the low-energy properties and characteristic Kondo energy scale of a triangular triple quantum dot, connected to two non-interacting leads, in a wide parameter range of a gate voltage and distortions which lower the symmetry of an equilateral structure, using the numerical renormalization group approach. For large Coulomb interactions, the ground states with different characters can be classified according to the plateaus of Θ≡(δe-δo)(2/π), where δe and δo are the phase shifts for the even and odd partial waves. At these plateaus of Θ, both Θ and the occupation number Ntot≡(δe+δo)(2/π) take values close to integers, and thus the ground states can be characterized by these two integers. The Kondo effect with a local moment with total spin S=1 due to a Nagaoka mechanism appears on the plateau, which can be identified by Θ≃2.0 and Ntot≃4.0. For large distortions, however, the high-spin moment disappears through a singlet-triplet transition occurring within the four-electron region. It happens at a crossover to the adjacent plateaus for Θ≃0.0 and Θ≃4.0, and the two-terminal conductance has a peak in the transient regions. For weak distortions, the SU(4) Kondo effect also takes place for Ntot≃3.0. It appears as a sharp conductance valley between the S=1/2 Kondo ridges on both sides. We also find that the characteristic energy scale T* reflect these varieties of the Kondo effect. Particularly, T* is sensitive to the distribution of the charge and spin in the triangular triple dot.
Hydration-induced spin-glass state in a frustrated Na-Mn-O triangular lattice
Bakaimi, Ioanna; Brescia, Rosaria; Brown, Craig M.; Tsirlin, Alexander A.; Green, Mark A.; Lappas, Alexandros
2016-05-01
Birnessite compounds are stable across a wide range of compositions that produces a remarkable diversity in their physical, electrochemical, and functional properties. These are hydrated analogs of the magnetically frustrated, mixed-valent manganese oxide structures, with general formula, N axMn O2 . Here we demonstrate that the direct hydration of layered rock-salt type α-NaMn O2 , with the geometrically frustrated triangular lattice topology, yields the birnessite type oxide, N a0.36Mn O2.0.2 H2O , transforming its magnetic properties. This compound has a much-expanded interlayer spacing compared to its parent α-NaMn O2 compound. We show that while the parent α-NaMn O2 possesses a Néel temperature of 45 K as a result of broken symmetry in the M n3 + sublattice, the hydrated derivative undergoes collective spin freezing at 29 K within the M n3 +/M n4 + sublattice. Scaling-law analysis of the frequency dispersion of the ac susceptibility, as well as the temperature-dependent, low-field dc magnetization confirm a cooperative spin-glass state of strongly interacting spins. This is supported by complementary spectroscopic analysis [high-angle annular dark-field scanning transmission electron miscroscopy (TEM), energy-dispersive x-ray spectroscopy, and electron energy-loss spectroscopy] as well as by a structural investigation (high-resolution TEM, x-ray, and neutron powder diffraction) that yield insights into the chemical and atomic structure modifications. We conclude that the spin-glass state in birnessite is driven by the spin frustration imposed by the underlying triangular lattice topology that is further enhanced by the in-plane bond-disorder generated by the mixed-valent character of manganese in the layers.
Magnetic excitations in the triangular antiferromagnets Mn3Sn and Mn3Ge
Cable, J. W.; Wakabayashi, N.; Radhakrishna, P.
1993-09-01
Inelastic neutron scattering was used to study the magnetic excitations of the triangular antiferromagnets Mn3Sn and Mn3Ge. These compounds have itinerant d electrons and large magnetic moments localized at the Mn sites and may be regarded as materials that lie in the intermediate regime between local-moment and itinerant-electron systems. The spin-wave spectra exhibit steep dispersion and strong damping, which is characteristic behavior of itinerant-electron systems. Nevertheless, it is useful to analyze the data in terms of a local-moment model with anisotropy. We find the data are remarkably well described by this model with exchange parameters extending to fifth-nearest neighbors and with both axial- and basal-plane anisotropy. The axial-anisotropy parameters were determined from the uniform out-of-plane spin fluctuation, and the signs show that the spins are confined to the basal plane. The second-order basal-plane anisotropy constants were determined by satisfying both the magnitude of the weak basal-plane ferromagnetic moments and the observed splitting of a doubly degenerate acoustic-spin-wave branch. The sixth-order basal-plane anisotropy was determined by adjusting to the observed energy gap associated with spin fluctuations within the basal plane. The exchange parameters have the correct signs to stabilize the triangular antiferromagnetic structure but yield Néel temperatures that are higher than those observed by a factor of 3 or 4. This overestimation of the Néel temperature is not an uncommon result when a local moment model is applied to an itinerant-electron system.
Spin liquid state in the disordered triangular lattice Sc2Ga2CuO7 revealed by NMR
Khuntia, P.; Kumar, R.; Mahajan, A. V.; Baenitz, M.; Furukawa, Y.
2016-04-01
We present microscopic magnetic properties of a two-dimensional triangular lattice Sc2Ga2CuO7 , consisting of single and double triangular Cu planes. An antiferromagnetic (AFM) exchange interaction J /kB≈35 K between Cu2 + (S =1 /2 ) spins in the triangular biplane is obtained from the analysis of intrinsic magnetic susceptibility data. The intrinsic magnetic susceptibility, extracted from 71Ga NMR shift data, displays the presence of AFM short range spin correlations and remains finite down to 50 mK, suggesting a nonsinglet ground state. The nuclear spin-lattice relaxation rate (1 /T1 ) reveals a slowing down of Cu2 + spin fluctuations with decreasing T down to 100 mK. Magnetic specific heat (Cm) and 1 /T1 exhibit power law behavior at low temperatures, implying the gapless nature of the spin excitation spectrum. The absence of long range magnetic ordering down to ˜J /700 , nonzero spin susceptibility at low T , and the power law behavior of Cm and 1 /T1 suggest a gapless quantum spin liquid (QSL) state. Our results demonstrate that persistent spin dynamics induced by frustration maintain a quantum-disordered state at T →0 in this triangular lattice antiferromagnet. This suggests that the low energy modes are dominated by spinon excitations in the QSL state due to randomness engendered by disorder and frustration.
Directory of Open Access Journals (Sweden)
Noriyuki Hirota, Tsutomu Ando, Ryo Tanaka, Hitoshi Wada and Yoshio Sakka
2009-01-01
Full Text Available We studied methods of controlling the spacing between particles in the triangular lattice formed by feeble magnetic particles through induced magnetic dipole interaction. Formation of a triangular lattice is described by the balance between the magnetic force and the interaction of induced magnetic dipoles. The intensity of the magnetic force is proportional to the volume of particles V and the difference in the magnetic susceptibilities between the particles and the surrounding medium Δχ. On the other hand, the intensity of the induced magnetic dipole interaction depends on the square of V and Δχ. Therefore, altering the magnetic susceptibility difference by changing the susceptibility of the surrounding medium, volume of the particles, and intensity and spatial distribution of the applied magnetic field effectively controls the distance between the particles. In this study, these three methods were evaluated through experiment and molecular dynamics simulations. The distance between the particles, i.e. the lattice constant of the triangular lattice, was varied from 1.7 to 4.0 in units of the particle diameter. Formation of self-organized triangular lattice through the induced magnetic dipole interaction is based on magnetism, a physical property that all materials have. Therefore, this phenomenon is applicable to any materials of any size. Consequently, structure formation through induced magnetic dipole interaction is a potential way of fabricating materials with ordered structures.
Institute of Scientific and Technical Information of China (English)
SUN Lian-Liang; LI Shu-Shen
2005-01-01
@@ We theoretically investigate the energy spectra of two-electron two-dimensional (2e 2D) quantum dots (QDs)confined by triangular potentials and bowl-like potentials in a magnetic field by exact diagonalization in the framework of effective mass theory. An in-plane electric field is found to contribute to the singlet-triplet transition of the ground state of the 2e 2D QDs confined by triangular or bowl-like potentials in a perpendicular magnetic field. The stronger the in-plane electric field, the smaller the magnetic field for the total spin of the ground states in the dot systems to change from S = 0 to S = 1. However, the influence of anin-plane electric field on the singlettriplet transition of the ground state of two electrons in a triangular QD modulated by a perpendicular magnetic field is quite small because the triangular potential just deviates from the harmonic potential well slightly. We find that the strength of the perpendicular magnetic field needed for the spin singlet-triplet transition of the ground state of the QD confined by a bowl-like potential is reduced drastically by applying an in-plane electric field.
Koehrsen, Craig L. (Inventor)
2000-01-01
A site database structure for storing elevation data for access by an application program being executed on a control system on a work machine. The data is stored in a Triangular Irregular Network (TIN). The elevation of a point on the work site based on the three points forming the triangle containing the point.
Indian Academy of Sciences (India)
Jagadish Singh; Joel John Taura
2014-06-01
We have examined the effects of oblateness up to 4 of the less massive primary and gravitational potential from a circum-binary belt on the linear stability of triangular equilibrium points in the circular restricted three-body problem, when the more massive primary emits electromagnetic radiation impinging on the other bodies of the system. Using analytical and numerical methods, we have found the triangular equilibrium points and examined their linear stability. The triangular equilibrium points move towards the line joining the primaries in the presence of any of these perturbations, except in the presence of oblateness up to 4 where the points move away from the line joining the primaries. It is observed that the triangular points are stable for 0 < < c and unstable for c ≤ ≤ $\\frac{1}{2}$, where c is the critical mass ratio affected by the oblateness up to 4 of the less massive primary, electromagnetic radiation of the more massive primary and potential from the belt, all of which have destabilizing tendencies, except the coefficient 4 and the potential from the belt. A practical application of this model could be the study of motion of a dust particle near a radiating star and an oblate body surrounded by a belt.
Schoedel, Alexander
2013-02-10
The self-assembly of triangular, tetrahedral, and trigonal-prismatic molecular building blocks affords the first example of a trinodal family of metal-organic materials. Four examples of isoreticular expanded and functionalized frameworks are detailed. Gas adsorption experiments validated the permanent porosity of the parent structure. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Molecular electrostatic potential analysis of non-covalent complexes
Indian Academy of Sciences (India)
PADINJARE VEETIL BIJINA; CHERUMUTTATHU H SURESH
2016-10-01
Ab initio MP4/Aug-cc-pvDZ//MP2/6-311++g(d,p) level interaction energy (Eint) and molecular electrostatic potential analysis (MESP) of a large variety of non-covalent intermolecular complexes, viz. tetrel, chalcogen, pnicogen, halogen, hydrogen, dihydrogen and lithium bonded complexes have been reported. The electronic changes associated with the non-covalent complex formation is monitored in terms of MESP minimum (Vmin) in the free and complexed states of the donor and acceptor molecules as well as in terms ofMESP at the donor and acceptor atoms (Vn) of the free monomers and complexes. The change in Vmin or Vn on the donor molecule (ΔVmin(D) or ΔVn(D)) during complex formation is proportional to its electron donating ability while such a change on the acceptor molecule (ΔVmin(A) or ΔVn(A)) is proportional to its electron accepting ability. Further, the quantities ΔΔVmin = ΔVmin(D) −ΔVmin(A) and ΔΔVn = ΔVn(D) −ΔVn(A) have shown strong linear correlations with Eint of the complex (Eint values fall in the range 0.7 to 46.2 kcal/mol for 54 complexes) and suggest that the intermolecular non-covalent interactions in a wide variety of systems can be monitored and assessed in terms of change in MESP due to complex formation in the gas phase. With the incorporation of solvent effect in the calculation, charged systems showed significant deviations from the linear correlation. The MESP based analysis proposes that the large variety of intermolecular non-covalent complexes considered in this study can be grouped under the general category of electron donor-acceptor (eDA) complexes
Triangular coupling of SCDAP/Lower Head/RELAP5 using parallel virtual machine
International Nuclear Information System (INIS)
The present integrated SCDAP/RELAP5 MOD3.2 computer code is used for the simulation of reactor coolant system thermal-hydraulic (T/H) response and core damage progression. Due to the size of the code (∼150,000 lines), maintenance and upgrades present a significant burden. For the user, the code structure and data communication is difficult to understand, thus making it difficult to track down problems that arise during severe accident analyses. Adding to this difficulty is the fact that typical simulations can take anywhere from a few days to several weeks to complete. Therefore, in an effort to reduce the maintenance burden and enhance code performance, a change in the code structure was required. The U.S. Nuclear Regulatory Commission (USNRC) and the Swiss Federal Nuclear Safety Inspectorate (HSK), with technical assistance from SCIENTECH, Inc. and the Idaho Engineering and Environmental Laboratory (INEEL) initiated a concept of a triangular coupling of sub-modules within the SCDAP/RELAP5 MOD3.2 code: SCDAP, Lower Head (LOWHD), and RELAP5. The goal was to cleanly separate the SCDAP, LOWHD, and RELAP5 modules from the integrated SCDAP/RELAP5 code and then link these code modules using the Parallel Virtual Machine (PVM) software package. This triangular coupling using PVM is now successfully completed, and will facilitate the coupling of SCDAP/LOWHD with the new generation of thermal hydraulic codes, such as TRAC-M. With regard to parallel performance, this work is only a first step towards obtaining significant performance improvements. Further efforts will be required to fully realize these parallel performance gains. These are the further goals the USNRC and HSK propose to follow in the near future. The coupled code was verified by comparing results with those of the original merged code (i.e. the code as it existed prior to separating the three codes). First, three relatively simple developmental assessment cases were run, including a bundle boil
Indian Academy of Sciences (India)
K K Verma; K R Soni
2005-09-01
The radiation characteristics of a two-element array of equilateral triangular patch microstrip antenna on a ferrite substrate are studied theoretically by considering the presence of bias magnetic field in the direction of propagation of electromagnetic waves. It is found that the natural modes of propagation in the direction of magnetic field are left- and right-circularly polarized waves and these modes have different propagation constants. In loss-less isotropic warm plasma, this array antenna geometry excites both electromagnetic (EM) and electroacoustic plasma (P) waves in addition to a nonradiating surface wave. In the absence of an external magnetic field, the EM- and P-waves can be decoupled into two independent modes, the electroacoustic mode is longitudinal while the electromagnetic mode is transverse. The far-zone EM-mode and P-mode radiation fields are derived using vector wave function techniques and pattern multiplication approaches. The results are obtained in both plasma medium and free space. Some important antenna parameters such as radiation conductance, directivity and quality factor are plotted for different values of plasma-to-source frequency.
Semiclassical theory of the magnetization process of the triangular lattice Heisenberg model
Coletta, Tommaso; Tóth, Tamás A.; Penc, Karlo; Mila, Frédéric
2016-08-01
Motivated by the numerous examples of 1/3 magnetization plateaux in the triangular-lattice Heisenberg antiferromagnet with spins ranging from 1/2 to 5/2, we revisit the semiclassical calculation of the magnetization curve of that model, with the aim of coming up with a simple method that allows one to calculate the full magnetization curve and not just the critical fields of the 1/3 plateau. We show that it is actually possible to calculate the magnetization curve including the first quantum corrections and the appearance of the 1/3 plateau entirely within linear spin-wave theory, with predictions for the critical fields that agree to order 1 /S with those derived a long time ago on the basis of arguments that required going beyond linear spin-wave theory. This calculation relies on the central observation that there is a kink in the semiclassical energy at the field where the classical ground state is the collinear up-up-down structure and that this kink gives rise to a locally linear behavior of the energy with the field when all semiclassical ground states are compared to each other for all fields. The magnetization curves calculated in this way for spin 1/2, 1, and 5/2 are shown to be in good agreement with available experimental data.
Solution adaptive triangular meshes with application to the simulation of plasma equilibrium
International Nuclear Information System (INIS)
A new discrete Laplace operator is constructed on a local mesh molecule, second order accurate on symmetric cell regions, based on local Taylor series expansions. This discrete Laplacian is then compared to the one commonly used in the literature. A truncation error analysis of gradient and Laplace operators calculated at triangle centroids reveals that the maximum bounds of their truncation errors are minimized on equilateral triangles, for a fixed triangle perimeter. A new adaptive strategy on arbitrary triangular grids is developed in which a uniform grid is defined with respect to the solution surface, as opposed to the x,y plane. Departures from mesh uniformity arises from a spacially dependent mean-curvature of the solution surface. The power of this new adaptive technique is applied to the problem of finding free-boundary plasma equilibria within the context of MHD. The geometry is toroidal, and axisymmetry in the toroidal direction is assumed. We are led to conclude that the grid should move, not towards regions of high curvature of magnetic flux, but rather towards regions of greater toroidal current density. This has a direct bearing on the accuracy with which the Grad-Shafranov equation is being approximated
A novel algorithm for explicit optimal multi-degree reduction of triangular surfaces
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
This paper introduces the algebraic property of bivariate orthonormal Jacobi polynomials into geometric approximation. Based on the latest results on the transformation formulae between bivariate Bernstein polynomials and Jacobi polynomials, we naturally deduce a novel algorithm for multi-degree reduction of triangular Bézier surfaces. This algorithm possesses four characteristics: ability of error forecast, explicit expression, less time consumption, and best precision. That is, firstly, whether there exists a multi-degree reduced surface within a prescribed tolerance is judged beforehand; secondly, all the operations of multi-degree reduction are just to multiply the column vector generated by sorting the series of the control points of the original surface in lexicographic order by a matrix; thirdly, this matrix can be computed at one time and stored in an array before processing degree reduction; fourthly, the multi-degree reduced surface achieves an optimal approximation in the norm L2. Some numerical experiments are presented to validate the effectiveness of this algorithm, and to show that the algorithm is applicable to information processing of products in CAD system.
Hasheminejad, S. M.
2016-01-05
A series of flow visualizations were conducted to qualitatively study the development of streamwise counter-rotating vortices over a flat plate induced by triangular patterns at the leading edge of a flat plate. The experiments were carried out for a Reynolds number based on the pattern wavelength (λ) of 3080. The results depict the onset, development and breakdown of the vortical structures within the flat plate boundary layer. Moreover, the effect of one spanwise array of holes with diameter of 0.2λ (=3 mm) was examined. This investigation was done on two different flat plates with holes placed at the location x/λ = 2 downstream of the troughs and peaks. The presence of holes after troughs does not show any significant effect on the vortical structures. However, the plate with holes after peaks noticeably delays the vortex breakdown. In this case, the “mushroom-like” vortices move away from the wall and propagate downstream with stable vortical structures. The vortex growth is halted further downstream but start to tilt aside.
Laminar Natural Convection of Newtonian and Non Newtonian Fluids Inside Triangular Enclosure
Directory of Open Access Journals (Sweden)
Ala?a Abbas Muhadi
2007-01-01
Full Text Available In the present work, steady two dimensional laminar natural convection heat transfer of Newtonian and non-Newtonian fluids inside isosceles triangular enclosure has been analyzed numerically for a wide range of the modified Rayleigh numbers of (103 ≤ Ra ≤ 105, with non-dimensional parameter (NE of Prandtl Eyring model ranging from (0 to 10, and modified Prandtl number take in the range (Pr* =1,10, and 100. Two types of boundary conditions have been considered. The first, when the inclined walls are heated with different uniform temperatures and the lower wall is insulated. The second, when the bottom wall is heated by applying a uniform heat flux while the inclined walls at the constant cold temperature. Also, the non-Newtonian fluids under consideration were assumed to obey the Prandtl Eyring model..The results are presented in terms of isotherms and streamlines to show the behavior of the fluid flow and temperature fields. In addition, some graphics are presented the relation between average Nusselt number and the various parameters. The results show the effect of non dimensional parameter (NE on the velocity and temperature profiles. They also show that the average Nusselt number is a strong function of modified Rayleigh number, modified Prandtl number, non-dimensional parameter, and the boundary conditions. Four different correlations have been made to show the dependence of the average Nusselt number on the non-dimensional parameter, the modified Rayleigh and Prandtl numbers.
Franz, Silvio; Gradenigo, Giacomo; Spigler, Stefano
2016-03-01
We study how the thermodynamic properties of the triangular plaquette model (TPM) are influenced by the addition of extra interactions. The thermodynamics of the original TPM is trivial, while its dynamics is glassy, as usual in kinetically constrained models. As soon as we generalize the model to include additional interactions, a thermodynamic phase transition appears in the system. The additional interactions we consider are either short ranged, forming a regular lattice in the plane, or long ranged of the small-world kind. In the case of long-range interactions we call the new model the random-diluted TPM. We provide arguments that the model so modified should undergo a thermodynamic phase transition, and that in the long-range case this is a glass transition of the "random first-order" kind. Finally, we give support to our conjectures studying the finite-temperature phase diagram of the random-diluted TPM in the Bethe approximation. This corresponds to the exact calculation on the random regular graph, where free energy and configurational entropy can be computed by means of the cavity equations.
Iterative Process to Improve Simple Adaptive Subdivision Surfaces Method for Triangular Meshes
Directory of Open Access Journals (Sweden)
Noor A. Husain
2011-01-01
Full Text Available Problem statement: Subdivision surfaces were applied to the entire meshes in order to produce smooth surfaces refinement from coarse mesh. Several schemes had been introduced in this area to provide a set of rules to converge smooth surfaces. However, to compute and render all the vertices are really inconvenient in terms of memory consumption and runtime during the subdivision process. It will lead to a heavy computational load especially at a higher level of subdivision. Adaptive subdivision is a method that subdivides only at certain areas of the meshes. Although subdivision occurs at the selected areas, quality of produced surfaces can be preserved similar to a regular subdivision surfaces. Nevertheless, adaptive subdivision process suffers because of two reasons; calculations need to be done to define areas that required to be subdivided and to remove cracks created from the subdivision depth difference between selected and unselected areas. Cracks must be removed because it creates artifacts in editing, rendering and processing of the mesh. Approach: This research brings to iterative adaptive subdivision to improve simple adaptive subdivision surfaces method for triangular meshes. Results: The result of this iterative process presented to produce fewer polygons while it preserve smoother. Conclusion: The proposed method created surfaces of better quality, computationally more efficient and occupied less memory as compared to original method.
TAILORING OF FLATTENED DISPERSION IN TRIANGULAR-LATTICE PHOTONIC CRYSTAL FIBER
Directory of Open Access Journals (Sweden)
Sandhir Kumar Singh
2011-12-01
Full Text Available The interest of researchers and engineers in several laboratories, since the1980s, has been attracted by the ability to structure materials on the scale of the optical wavelength, a fraction of micrometers or less, in order to develop new optical medium, known as photonic crystals . Photonic crystals rely on a regular morphological microstructure of air-holes, incorporated into the material, which radically alters its optical properties. In Photonic Crystal Fiber (PCF it is possible to realize flat dispersion over a wide wavelength range that cannot be realized with a conventional single-mode fiber. In PCFs, the dispersion can be controlled and tailored with unprecedented freedom. In fact, due to the high refractive index difference between silica and air, and to the flexibility of changing air-hole sizes and patterns, the waveguide contribution to the dispersion parameter can be significantly changed, thus obtaining unusual position of the zero dispersion wavelength, as well as particular values of the dispersion curve slope. In particular, by manipulating the air- hole radius or the lattice period of the micro structured cladding, it is possible to control the zero-dispersion wavelength, which can be tuned over a very wide range, or the dispersion curves, which can be engineered to be ultra flattened. In this paper the geometric parameters of triangular PCF have been properly changed to optimize the dispersion compensation over a wide wavelength range.
Calculation of the elastic properties of a triangular cell core for lightweight composite mirrors
Penado, F. Ernesto; Clark, James H., III; Walton, Joshua P.; Romeo, Robert C.; Martin, Robert N.
2007-09-01
The use of composite materials in the fabrication of optical telescope mirrors offers many advantages over conventional methods, including lightweight, portability and the potential for lower manufacturing costs. In the construction of the substrate for these mirrors, sandwich construction offers the advantage of even lower weight and higher stiffness. Generally, an aluminum or Nomex honeycomb core is used in composite applications requiring sandwich construction. However, the use of a composite core offers the potential for increased stiffness and strength, low thermal distortion compatible with that of the facesheets, the absence of galvanic corrosion and the ability to readily modify the core properties. In order to design, analyze and optimize these mirrors, knowledge of the mechanical properties of the core is essential. In this paper, the mechanical properties of a composite triangular cell core (often referred to as isogrid) are determined using finite element analysis of a representative unit cell. The core studied offers many advantages over conventional cores including increased thermal and dimensional stability, as well as low weight. Results are provided for the engineering elastic moduli of cores made of high stiffness composite material as a function of the ply layup and cell size. Finally, in order to illustrate the use of these properties in a typical application, a 1.4-m diameter composite mirror is analyzed using the finite element method, and the resulting stiffness and natural frequencies are presented.
Evolution of elliptic and triangular flow as a function of beam energy in a hybrid model
Auvinen, Jussi
2013-01-01
Elliptic flow has been one of the key observables for establishing the finding of the quark-gluon plasma (QGP) at the highest energies of Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). As a sign of collectively behaving matter, one would expect the elliptic flow to decrease at lower beam energies, where the QGP is not produced. However, in the recent RHIC beam energy scan, it has been found that the inclusive charged hadron elliptic flow changes relatively little in magnitude in the energies between 7.7 and 39 GeV per nucleon-nucleon collision. We study the collision energy dependence of the elliptic and triangular flow utilizing a Boltzmann + hydrodynamics hybrid model. Such a hybrid model provides a natural framework for the transition from high collision energies, where the hydrodynamical description is essential, to smaller energies, where the hadron transport dominates. This approach is thus suitable to investigate the relative importance of these two mechanisms for the produ...
Energy Technology Data Exchange (ETDEWEB)
Haghbin, S.; Farahat, S. [Sistan and Baluchestan Univ., Dept. of Mechanical Engineering, Zahedan (Iran, Islamic Republic of)]. E-mail: sadegh_haghbin@yahoo.com
2004-07-01
In this paper, the numerical solution of two-dimensional incompressible viscid flow by triangular unstructured grid around airfoil with dynamic ground effect and by using geometric conservation law (GCL) has been represented. In this analysis, after the mesh generation for physical model, for the purpose of adaption of meshes with physical condition, the mesh adaption method has been used. Also, for increasing the speed of results convergence, the Multigrid method has been applied to the solver of governing equations. Because of the movement of meshes in this analysis, by using a spring simulation, the generated meshes have been moved and in every time step for the purpose of controlling the quality of meshes, by considering the EquiAngle Skew coefficient (EAS) and the volume of each mesh, the meshes that had a large EAS and a volume more than and less than defined maximum and minimum value, have been removed and then regenerated. Also, because the continuity and momentum conservations law were insufficient to work with these moving grids, the geometric conservation law was combined with the other conservation laws and a general equation was obtained for the dynamic meshes. For solving this general equation, the Simple Algorithm has been used. According to the results, the dynamic ground effect causes unsteadiness and also the Lift coefficient is increased vibrationally. And with respect to the type of airfoil, the Drag coefficient can decrease or increase vibrationally. (author)
Tricriticality of the Blume-Emery-Griffiths model in thin films of stacked triangular lattices
El Hog, Sahbi; Diep, H. T.
2016-03-01
We study in this paper the Blume-Emery-Griffiths model in a thin film of stacked triangular lattices. The model is described by three parameters: bilinear exchange interaction between spins J, quadratic exchange interaction K and single-ion anisotropy D. The spin Si at the lattice site i takes three values (-1, 0, +1). This model can describe the mixing phase of He-4 (Si = +1,-1) and He-3 (Si = 0) at low temperatures. Using Monte Carlo simulations, we show that there exists a critical value of D below (above) which the transition is of second-(first-)order. In general, the temperature dependence of the concentrations of He-3 is different from layer by layer. At a finite temperature in the superfluid phase, the film surface shows a deficit of He-4 with respect to interior layers. However, effects of surface interaction parameters can reverse this situation. Effects of the film thickness on physical properties will be also shown as functions of temperature.
Tunability of Triangular SRR and Wire Strip (TSRR-WS Metamaterial at THz
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Parul Dawar
2014-01-01
Full Text Available This paper adumbrates a novel tunable metamaterial consisting of triangular split ring resonator (TSRR and wire strip (WS at THz frequency. Ansoft high frequency structure simulator (HFSS has been used to design and analyse the metamaterial having Rogers RT/duroid 5870 (εr = 2.33 and FR4 (εr = 4.4 as substrate material. Nicolson Ross Weir (NRW method has been used to retrieve the material parameters from transmission and reflection coefficient. 4% maximization has been obtained in the location of the negative region (or resonance frequency for permeability by using FR4 with 0.75 μm instead of 1.25 μm as substrate thickness. In addition, 18% minimization has been achieved by using FR4 with 0.25 μm instead of RT/duroid 5870 substrate with the same thickness. Tunability has been proved by showing dependence of resonant frequency over the substrate thickness and substrate material.
Superglass Phase of Interaction-Blockaded Gases on a Triangular Lattice
Angelone, Adriano; Mezzacapo, Fabio; Pupillo, Guido
2016-04-01
We investigate the quantum phases of monodispersed bosonic gases confined to a triangular lattice and interacting via a class of soft-shoulder potentials. The latter correspond to soft-core potentials with an additional hard-core onsite interaction. Using exact quantum Monte Carlo simulations, we show that the low temperature phases for weak and strong interactions following a temperature quench are a homogeneous superfluid and a glass, respectively. The latter is an insulating phase characterized by inhomogeneity in the density distribution and structural disorder. Remarkably, we find that for intermediate interaction strengths a superglass occurs in an extended region of the phase diagram, where glassy behavior coexists with a sizable finite superfluid fraction. This glass phase is obtained in the absence of geometrical frustration or external disorder and is a result of the competition of quantum fluctuations and cluster formation in the corresponding classical ground state. For high enough temperature, the glass and superglass turn into a floating stripe solid and a supersolid, respectively. Given the simplicity and generality of the model, these phases should be directly relevant for state-of-the-art experiments with Rydberg-dressed atoms in optical lattices.
Design of Compact EBG Structure and effect on Circularly Polarized Triangular Patch with Stub
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Snehalata Chokat,
2012-05-01
Full Text Available This paper presents the study of electromagnetic band gap (EBG structure using slot ring and its effect oncircularly polarized triangular patch antenna performance. The EBG structure has been designed on dielectricsubstrate εr=4.3 and thickness h=1.53mm. The EBG structure acts as resonator which attenuates the surfacewave propagation in a specific frequency range. A new single slot ring EBG structure is proposed whichexhibits surface wave attenuation better than 20 dB in the frequency range from 2.75 GHz to 3.2 GHz. Anantenna with center frequency of 2.8 GHz is designed with and without EBG. The peak gain and radiation efficiency of this antenna are mproved significantly when antenna is above EBG in comparison to ntenna without EBG. The simulated adiation patterns of the antenna xhibit reduction in backward adiation when antenna above EBG plane n comparison to radiation pattern without EBG. Keywords- ctromagnetic band gap (EBG, periodic structures, fractal geometry, platting through hole (PTH, microstrip antenna, and surface wave suppression.
Jacob, Jesly; R, Ajith; Mathew, Vincent
2011-11-20
The optical near-field surface plasmon effects of a triangular system of silver nanoshell cylinders are numerically studied using the two-dimensional finite difference time domain method. The dependence of interparticle distance, shell thickness of the cylinder, dielectric constant of shell core as well as embedding medium, and orientation of the optical source plane on the plasmonic resonances of the nanocylinder shells is studied. The plasmonic resonances are found to have strong dependence on the interparticle distance. As the size of the particle is increased, the field intensity peak shows a redshift. The resonance condition varies with the dielectric constant of the environment as well as the core. In addition, the orientation of the incident source plane has a significant role in the near-field intensity distribution. Since the near-field intensity has the same trend as that of the scattering cross section, the results can be used in the design of various applications like sensing, antennas, and waveguides. PMID:22108888
Magnetic properties of two dimensional silicon carbide triangular nanoflakes-based kagome lattices
Energy Technology Data Exchange (ETDEWEB)
Li Xiaowei [Peking University, Center for Applied Physics and Technology, College of Engineering (China); Zhou Jian [Peking University, Department of Materials Science and Engineering (China); Wang Qian, E-mail: qianwang2@pku.edu.cn [Peking University, Center for Applied Physics and Technology, College of Engineering (China); Jena, Puru [Virginia Commonwealth University, Department of Physics (United States)
2012-08-15
Two-dimensional (2D) magnetic kagome lattices are constructed using silicon carbide triangular nanoflakes (SiC-TNFs). Two types of structures with alternating Si and C atoms are studied: the first one is constructed using the C-edged SiC-TNFs as the building blocks and C atoms as the linkers of kagome sites (TNF{sub N}-C-TNF{sub N}) while the second one is composed of the Si-edged SiC-TNFs with Si atoms as linkers (TNF{sub N}-Si-TNF{sub N}). Using density functional theory-based calculations, we show that the fully relaxed TNF{sub N}-C-TNF{sub N} retains the morphology of regular kagome lattice and is ferromagnetism. On the other hand, the TNF{sub N}-Si-TNF{sub N} structure is deformed and antiferromagnetic. However, the ground state of TNF{sub N}-Si-TNF{sub N} structure can be transformed from the antiferromagnetic to ferromagnetic state by applying tensile strain. Monte Carlo simulations indicate that the SiC-TNFs-based kagome lattices can be ferromagnetic at room temperature.
Structure and evolution of strange attractors in non-elastic triangular billiards
Arroyo, Aubin; Sanders, David P
2011-01-01
We study pinball billiard dynamics in an equilateral triangular table. In such dynamics, collisions with the walls are non-elastic: the outgoing angle with the normal vector to the boundary is a uniform factor $\\lambda < 1$ smaller than the incoming angle. This leads to contraction in phase space for the discrete-time dynamics between consecutive collisions, and hence to attractors of zero Lebesgue measure, which are almost always fractal strange attractors with chaotic dynamics, due to the presence of an expansion mechanism. We study the structure of these strange attractors and their evolution as the contraction parameter $\\lambda$ is varied. For $\\lambda$ in the interval (0, 1/3), we prove rigorously that the attractor has the structure of a Cantor set times an interval, whereas for larger values of $\\lambda$ the billiard dynamics gives rise to nonaccessible regions in phase space. For $\\lambda$ close to 1, the attractor splits into three transitive components, the basins of attraction of which have fra...
Molecular Cloning and Sequence Analysis of IGF-I from Triangular Bream(Megalobrama terminalis)
Institute of Scientific and Technical Information of China (English)
TONG Fu-dan; LIU Hong-yun
2004-01-01
The insulin-like growth factor Ⅰ(IGF-Ⅰ)gene of triangular bream(Megalobrama terminalis)(GenBank No.AY247412)(Tb)was cloned for the first time from liver by RT-PCR. The nucleotide sequence analysis showed the Tb IGF-Ⅰ cDNA consisted of 486 nucleotides and encoded 117 amino acids including B,C,A,D and E five domains. Analysis of E-domain indicated that cloned Tb IGF-Ⅰ belonged to IGF-Ⅰ Ea-2 subtype. Identity analysis showed the IGF-Ⅰ nucleotide sequence shared 99.8% homology with bluntnose bream,88.8% with grass Carp,85.8% with common carp; the pre-IGF-Ⅰ amine acid sequence shared 99.4% with bluntnose bream,88.8% with grass carp,85.4% homology with common carp. In the Cyprinus Carpio,the higher homology of nucleotide sequence and amino acid sequence in IGF-Ⅰshowed that the closer relationship the fishes have. These results could provide basic data for the research on Tb germplasm and the development and utilization of biological feed additives.
Effect of wall proximity of two staggered triangular cylinders on the transport process in a channel
Directory of Open Access Journals (Sweden)
Mousa Farhadi
2016-09-01
Full Text Available A numerical investigation has been carried out to analyze the heat transfer and the flow field around two isothermal triangular cylinders of equal size placed staggered in a horizontal plane channel with adiabatic walls. Computations have been carried out for Reynolds numbers (based on triangle width 100, 250, and 350, lateral gap ratios (d/B 0, 0.5, and 1, and longitudinal gap ratios (S/B 1, 2, 3 and 4. The effect of longitudinal and lateral gap between obstacles and proximity of channel walls is investigated. Results show that when obstacles are placed in close vicinity of the channel's wall (d/B = 1, vortex shedding disappears at the downstream of triangles at Re = 100 and 250 at all S/B, but for Re = 350 creating and disappearing of the vortex shedding depend on the longitudinal gap ratio (S/B. Proximity of obstacles has more effect on the second triangle than the first triangle especially from longitudinal gap ratio equals 2, so that with approaching the channel wall, the Nusselt number for the first triangle decreases, while for the second triangle a different behavior is seen. Staggered arrangement causes the Nusselt number of the second triangle to become greater than the first triangle.
A Triangular Finite Element with First-derivative Continuity Applied to Fusion MHD Applications
International Nuclear Information System (INIS)
We describe properties of the reduced quintic triangular finite element. The expansion used in the element will represent a complete quartic polynomial in two dimensions, and thus the error will be of order h5 if the solution is sufficiently smooth. The quintic terms are constrained to enforce C1 continuity across element boundaries, allowing their use with partial differential equations involving derivatives up to fourth order. There are only three unknowns per node in the global problem, which leads to lower rank matrices when compared with other high-order methods with similar accuracy but lower order continuity. The integrations to form the matrix elements are all done in closed form, even for the nonlinear terms. The element is shown to be well suited for elliptic problems, anisotropic diffusion, the Grad-Shafranov-Schlter equation, and the time-dependent MHD or extended MHD equations. The element is also well suited for 3D calculations when the third (angular) dimension is represented as a Fourier series
Directory of Open Access Journals (Sweden)
Taoufik Ghabara
2007-01-01
Full Text Available Geometric optics approximation for emissivity from triangular surfaces was compared with exact scattering predictions from electromagnetic theory. Rigorous electromagnetic scattering theory was numerically formulated based on the differential method. We have used a numerical simulation of the emissivity of gold and tungsten for a wavelength equal 0.55 micron to explore the validity of the geometric optics. Surface parameter domains for the regions of accuracy of the geometric optics approximation are quantified and presented as functions of surface slope and roughness. Influence on the validity of the approximate method of multiple scattering, the shadowing effect and the cavity effect of metallic surface have been investigated. For the latter, our interest was focused on the mechanism that enhances the emissivity of an interface when ruling a grating. It has been seen that the mechanism responsible for the enhancement of the emissivity depends very much on the period of the grating. For gratings with a period much smaller than the wavelength, the roughness essentially behaves as a transition layer with a gradient of the optical index. For different period / wavelength ratio, we have found a good agreement between the differential method and the homogenization regime when the period was smaller.
Controlled van der Waals epitaxy of monolayer MoS2 triangular domains on graphene.
Ago, Hiroki; Endo, Hiroko; Solís-Fernández, Pablo; Takizawa, Rina; Ohta, Yujiro; Fujita, Yusuke; Yamamoto, Kazuhiro; Tsuji, Masaharu
2015-03-11
Multilayered heterostructures of two-dimensional materials have recently attracted increased interest because of their unique electronic and optical properties. Here, we present chemical vapor deposition (CVD) growth of triangular crystals of monolayer MoS2 on single-crystalline hexagonal graphene domains which are also grown by CVD. We found that MoS2 grows selectively on the graphene domains rather than on the bare supporting SiO2 surface. Reflecting the heteroepitaxy of the growth process, the MoS2 domains grown on graphene present two preferred equivalent orientations. The interaction between the MoS2 and the graphene induced an upshift of the Raman G and 2D bands of the graphene, while significant photoluminescence quenching was observed for the monolayer MoS2. Furthermore, photoinduced current modulation along with an optical memory effect was demonstrated for the MoS2-graphene heterostructure. Our work highlights that heterostructures synthesized by CVD offer an effective interlayer van der Waals interaction which can be developed for large-area multilayer electronic and photonic devices. PMID:25695865
Wrześniewski, Kacper; Weymann, Ireneusz
2015-07-01
We analyze the spin-resolved transport properties of a triangular quantum dot molecule weakly coupled to external ferromagnetic leads. The calculations are performed by using the real-time diagrammatic technique up to the second-order of perturbation theory, which enables a description of both the sequential and cotunneling processes. We study the behavior of the current and differential conductance in the parallel and antiparallel magnetic configurations, as well as the tunnel magnetoresistance (TMR) and the Fano factor in both the linear and nonlinear response regimes. It is shown that the transport characteristics depend greatly on how the system is connected to external leads. Two specific geometrical configurations of the device are considered—the mirror one, which possesses the reflection symmetry with respect to the current flow direction and the fork one, in which this symmetry is broken. In the case of first configuration we show that, depending on the bias and gate voltages, the system exhibits both enhanced TMR and super-Poissonian shot noise. On the other hand, when the system is in the second configuration, we predict a negative TMR and a negative differential conductance in certain transport regimes. The mechanisms leading to those effects are thoroughly discussed.
Hole Detection for Increasing Coverage in Wireless Sensor Network Using Triangular Structure
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Shahram Babaie
2012-01-01
Full Text Available The emerging technology of wireless sensor network (WSN is expected to provide a broad range of applications, such as battlefield surveillance, environmental monitoring, smart spaces and so on. The coverage problem is a fundamental issue in WSN, which mainly concerns with a fundamental question: How well a sensor field is observed by the deployed sensors? Mobility is exploited to improve area coverage in a kind of hybrid sensor networks. The main objective for using mobile sensor nodes is to heal coverage holes after the initial network deployment, when designing a hole healing algorithm, the following issues need to be addressed. First, how to decide the existence of a coverage hole and how to estimate the size of a hole. Second, what are the best target locations to relocate mobile nodes to repair coverage holes? We use the triangular oriented diagram (HSTT for aim to goal where its simple ,have low calculation among construction and it is great to calculate the size of hole exactly .
RKKY interaction and local density of states for a triangular triple quantum dot system
Xiong, Yong-Chen; Wang, Wei-Zhong; Luo, Shi-Jun; Yang, Jun-Tao; Huang, Hai-Ming
2016-02-01
By means of the numerical renormalization group technique, we study the local density of states (LDOS) for a triangular triple quantum dot system, with two dots connected in parallel to the conduction leads. We find the location of the Ruderman-Kittel-Kasuya-Yosida (RKKY) peak identified in the LDOS could be illustrated as JRKKY = aΓ2 / U +bt22 / U, with U being the on-site Coulomb repulsion, Γ the dot-lead coupling, and t2 the hopping between the connected dots and the side dot. When the hopping between two connected dots t1 turns on, the spectrum weight of the RKKY peaks decreases due to the competition between the direct and the RKKY interactions. As t1 increases beyond a critical point t1c, two connected dots form a spin singlet, and decouple from both the side dot and the conduction leads, thus the Kondo and RKKY peaks could not be found. For t1 1 ≥t1 c, it drops to zero.
Phase diagram and low temperature scenario for a triangular triple dot system
Xiong, Yong-Chen; Wang, Wei-Zhong; Yang, Jun-Tao; Luo, Shi-Jun
2016-01-01
We present a triangular triple quantum dot (TTQD) system with two dots connected parallelly to one conduction lead, and investigate the phase diagram, the electric transport, and the temperature-dependent magnetic moment at half filling. When the hopping between two connected dots t12 = 0, and those between the connected dots and the side dot are symmetric t13 = t23, two connected dots form a spin triplet due to the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction mediated by the dot-lead coupling and/or the hopping t13 (t23). For t13 = 0, the triplet is partially screened by the conduction leads at low temperature. Both the connected dots and the side dot contribute to the magnetic moment of the system. For any definite t13, the triplet is totally screened by the conduction leads and the side dot, and the two-stage Kondo effect occurs. When t12 increases beyond a critical t12c, two connected dots form a spin singlet and decouple from the side dot. In this case, the Kondo peak is strongly suppressed, indicating zero conductance, and only the localized side dot contribute to the magnetic moment at low temperature. When t13 ≠ t23, we find a crossover as t12 increases, contrast to the first order transition of the symmetric case. Numerical renormalization group technique and physical arguments are used to obtain a detailed understanding of these problems.
Aerodynamic Stabilization of Flexible Optical Disk with Triangularly Arranged Stabilizer System
Aman, Yasutomo; Onagi, Nobuaki; Murata, Shozo; Uchida, Keisuke
2005-05-01
We have developed a flexible optical disk (FOD) system comprising a flexible disk and stabilizer, which can achieve a small axial runout of the disk through simplified stabilizer control. The approach adopts a new stabilizer system made up of triangularly arranged stabilizers (TASs), which consists of one main stabilizer (MS) that stabilizes the pickup focus area on the disk and two auxiliary stabilizers (ASs) that control the balancing conditions around the MS. We experimentally demonstrated that the TAS system could effectively stabilize a flexible disk even under conditions with no active stabilizer adjustments, such as axial position control and tilt control, which could not be eliminated in our previous single-stabilizer system. The suppressed axial runout without active adjustments was sufficiently small of less than 5 μm at linear velocities from 5.7 to 13.0 m/s up to double the speed of Blu-ray disk system. The results indicated that the FOD system with the TASs, which is easily operated, could be implemented in high-density optical disk systems with a high numerical-aperture (NA) pickup.
Directory of Open Access Journals (Sweden)
M.A. Ahmed
2015-09-01
Full Text Available In this paper, turbulent forced convection of nanofluids flow in triangular-corrugated channels is numerically investigated over Reynolds number ranges of 1000–5000. Four different types of nanofluids which are Al2O3, CuO, SiO2 and ZnO–water with nanoparticles diameters in the range of 30–70 nm and the range of nanoparticles volume fraction from 0% to 4% have been considered. The governing equations of mass, momentum and energy are solved using finite volume method (FVM. The low Reynolds number k–ε model of Launder and Sharma is adopted as well. It is found that the average Nusselt number, pressure drop, heat transfer enhancement, thermal–hydraulic performance increase with increasing in the volume fraction of nanoparticles and with decreasing in the diameter of nanoparticles. Furthermore, the SiO2–water nanofluid provides the highest thermal–hydraulic performance among other types of nanofluids followed by Al2O3, ZnO and CuO–water nanofluids. Moreover, the pure water has the lowest heat transfer enhancement as well as thermal–hydraulic performance.
Response properties in the adsorption-desorption model on a triangular lattice
Šćepanović, J. R.; Stojiljković, D.; Jakšić, Z. M.; Budinski-Petković, Lj.; Vrhovac, S. B.
2016-06-01
The out-of-equilibrium dynamical processes during the reversible random sequential adsorption (RSA) of objects of various shapes on a two-dimensional triangular lattice are studied numerically by means of Monte Carlo simulations. We focused on the influence of the order of symmetry axis of the shape on the response of the reversible RSA model to sudden perturbations of the desorption probability Pd. We provide a detailed discussion of the significance of collective events for governing the time coverage behavior of shapes with different rotational symmetries. We calculate the two-time density-density correlation function C(t ,tw) for various waiting times tw and show that longer memory of the initial state persists for the more symmetrical shapes. Our model displays nonequilibrium dynamical effects such as aging. We find that the correlation function C(t ,tw) for all objects scales as a function of single variable ln(tw) / ln(t) . We also study the short-term memory effects in two-component mixtures of extended objects and give a detailed analysis of the contribution to the densification kinetics coming from each mixture component. We observe the weakening of correlation features for the deposition processes in multicomponent systems.
Directory of Open Access Journals (Sweden)
A. Nagaraju
2015-04-01
Full Text Available Solar heat has been thrust area of research to explore renewable energy utilisation for the past few decades. In solar air heaters artificial roughness is tried on the surface of the absorber plate by adding small roughness elements to enhance the heat transfer rate. In the present work triangular protrusion are provided to act as roughness elements over the surface of the aluminum absorber plate. The experimental study is carried out on the effect of change in apex angle of protrusions on the heat transfer rate by keeping the other design parameters unchanged. Maximum heat transfer rate and thermo-hydraulic performance between the range of apex angle 300 and 600 is studied. The Nusselt number is between 50 and 110, friction factor 4.5-6.7x10-3 , Stanton number is 6- 14x10-3 . The heat transfer rate and thermo-hydraulic performance are observed to be maximum for 450 apex angle and least for the 600 plate.
Zeng, Qinghui; Li, Qin; Ji, Wenyu; Bin, Xue; Song, Jie
2016-05-01
With growing concerns about health issues worldwide, elegant sensors with high sensitivity and specificity for virus/antigens (Ag) detection are urgent to be developed. Homogeneous immunoassays (HIA) are an important technique with the advantages of small sample volumes requirement and pretreatment-free process. HIA are becoming more favorable for the medical diagnosis and disease surveillance than heterogeneous immunoassays. An important subset of HIA relies on the effect of fluorescence resonance energy transfer (FRET) via a donor-acceptor (D-A) platform, e.g., quantum dots (QDs) donor based FRET system. Being an excellent plasmonic material, silver triangular nanoplates (STNPs) have unique advantages in displaying surface plasmon resonance in the visible to near infrared spectral region, which make them a better acceptor for pairing with QDs in a FRET-based sensing system. However, the reported STNPs generally exhibited broad size distributions, which would greatly restrict their application as HIA acceptor for high detection sensitivity and specificity purpose. In this work, uniform STNPs and red-emitting QDs are firstly applied to construct FRET nanoplatform in the advanced HIA and further be exploited for analyzing virus Ag. The uniform STNPs/QDs nanoplatform based medical sensor provides a straightforward and highly sensitive method for Ag analysis in homogeneous form.
The Enigmatic Mushtikas and the Associated Triangular Terracotta Cakes: Some Observations
Directory of Open Access Journals (Sweden)
J. Manuel
2010-12-01
Full Text Available For over four decades, now, mushtikas and its common associate, the triangular terracotta cakes have been believed to be part of ‘fire altars’. This is, in spite of the fact that, either or both of these have been found from hearths, ovens, kilns, as flooring material, on walls, in passages, streets, bathrooms and therefore obviously near commodes. Further, the great variety of central stele and construction material, size and shape, materials found within ‘fire altars’ suggest that, all the above were devoid of religious symbolism and used to achieve domestic or industrial objectives. The cakes being primarily associated with run of the mill economic activities ended up in diverse and defiling contexts. However, like many cultures across time and space Harappans may also have used the medium of fire for offering sacrifices. Therefore the existence of ‘fire altars’ is not denied as such, but these then should not have the ubiquitous cakes, at the least.
Hole Detection for Increasing Coverage in Wireless Sensor Network Using Triangular Structure
Babaie, Shahram
2012-01-01
The emerging technology of wireless sensor network (WSN) is expected to provide a broad range of applications, such as battlefield surveillance, environmental monitoring, smart spaces and so on. The coverage problem is a fundamental issue in WSN, which mainly concerns with a fundamental question: How well a sensor field is observed by the deployed sensors? Mobility is exploited to improve area coverage in a kind of hybrid sensor networks. The main objective for using mobile sensor nodes is to heal coverage holes after the initial network deployment, when designing a hole healing algorithm, the following issues need to be addressed. First, how to decide the existence of a coverage hole and how to estimate the size of a hole. Second, what are the best target locations to relocate mobile nodes to repair coverage holes? We use the triangular oriented diagram (HSTT) for aim to goal where its simple, have low calculation among construction and it is great to calculate the size of hole exactly .
Estudo nacional dos atributos psicométricos da Escala Triangular do Amor de Sternberg
Directory of Open Access Journals (Sweden)
Vicente Cassepp-Borges
2012-04-01
Full Text Available A Escala Triangular do Amor de Sternberg (ETAS vem sendo a cada dia mais utilizada em pesquisas no Brasil. No entanto, todos seus estudos ocorreram a nível estadual. Este artigo teve como objetivo conhecer os atributos psicométricos da escala a nível nacional. A ETAS foi aplicada em uma amostra de 1.549 participantes de 13 Unidades da Federação brasileiras. Os resultados sugerem que a ETAS é um excelente teste, com a estrutura de três fatores prevista pela teoria e um elevado nível de precisão (α = 0,98. A Teoria de Resposta ao Item mostrou que a ETAS possui itens bastante discriminativos, avaliando uma boa faixa da população, embora com baixa dificuldade. Sugere-se a manutenção dos itens complexos na escala, com a finalidade de ter-se uma medida válida e precisa do amor.
Energy Technology Data Exchange (ETDEWEB)
Luwang, Meitram Niraj, E-mail: mn.luwang@ncl.res.in
2014-01-30
The triangular prism shapes of SnO{sub 2}·xH{sub 2}O nanoparticles are prepared using microemulsion route. The effect of variation of water pool value on the formation of SnO{sub 2} nanoparticles was studied. There is the quantum size effect in absorption study of SnO{sub 2} nanoparticles. With the increase of the water pool value, there is a decrease in the band edge absorption energy suggesting the weak quantum confinement effect (QCE) in SnO{sub 2} nanoparticles. Quenching effect increases with increase of water to surfactant ratio in luminescence. There is no significant effect in lifetime values for SnO{sub 2} nanoparticles in both microemulsion and powder form. SnO{sub 2} nanoparticles show green emission due to oxygen vacancy. SnO{sub 2} nanoparticles when doped with Eu{sup 3+} ions give the enhanced luminescence of Eu{sup 3+} due to the surface mediated energy transfer from SnO{sub 2} to Eu{sup 3+} ion.
Indian Academy of Sciences (India)
K K Verma; K R Soni
2005-01-01
The radiation properties of 2 × 2 element planar array of equilateral triangular patch microstrip antenna in plasma medium are studied. The array factor and far-zone EM-mode and P-mode radiation fields of the array geometry are derived using vector wave function techniques and pattern multiplication approaches. The total field patterns and various characteristics of pattern such as half power beam width (HPBW), first null beam width (FNBW) and direction of maximum radiation are computed for two different values of progressive phase excitation difference between the elements. The results of this array geometry are obtained both in plasma medium and in free space and compared with those of single element equilateral triangular patch microstrip antenna.
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Beatriz Gonçalves Brasileiro
2015-05-01
Full Text Available The purpose of this study was to evaluate the influence of planting and harvesting times on the polyphenol content and antioxidant capacity of Talinum triangulare cultivated during two different seasons (winter or summer and harvested 30 or 60 days after seedling establishment. Polyphenol content was quantified with the Folin-Ciocalteu method, and antioxidant activity was quantified with free-radical DPPH (1,1-diphenyl-2-picrilhidrazina. The highest levels of polyphenols were obtained from winter planting and from harvesting at 30 days. Antioxidant activity differed significantly in response to variation in planting and harvesting times, reaching 56.97% in extracts of plants produced in the winter and harvested at 30 days after planting. The times of planting and harvesting markedly influenced the content of polyphenols, and thus the antioxidant activity, of T. triangulare.
Singh, Jagadish; Emmanuel, A. Balogun
2014-09-01
The stability of triangular equilibrium points in the framework of the circular restricted three-body problem (CR3BP) is investigated for a test particle of infinitesimal mass in the vicinity of two massive bodies (primaries), when the bigger primary is a source of radiation and the smaller one is a triaxial rigid body with one of the axes as the axis of symmetry and its equatorial plane coinciding with the plane of motion, under the Poynting-Robertson (P-R) drag effect as a result of the radiating primary. It is found that the involved parameters influence the position of triangular points and their linear stability. It is noted that these points are unstable in the presence of Poynting-Robertson drag effect and conditionally stable in the absence of it.
Quantum Monte Carlo study of long-range transverse-field Ising models on the triangular lattice
Humeniuk, Stephan
2016-03-01
Motivated by recent experiments with a Penning ion trap quantum simulator, we perform numerically exact Stochastic Series Expansion quantum Monte Carlo simulations of long-range transverse-field Ising models on a triangular lattice for different decay powers α of the interactions. The phase boundary for the ferromagnet is obtained as a function of α . For antiferromagnetic interactions, there is strong indication that the transverse field stabilizes a clock ordered phase with sublattice magnetization (M ,-M/2 ,-M/2 ) with unsaturated M disorder" similar to the nearest-neighbor antiferromagnet on the triangular lattice. Connecting the known limiting cases of nearest-neighbor and infinite-range interactions, a semiquantitative phase diagram is obtained. Magnetization curves for the ferromagnet for experimentally relevant system sizes and with open boundary conditions are presented.
Institute of Scientific and Technical Information of China (English)
Abdullah H. AlEssa; Mohamad I. Al-Widyan
2008-01-01
This study examines the heat transfer enhancement from a horizontal rect- angular fin embedded with triangular perforations (their bases parallel and toward the fin tip) under natural convection. The fin's heat dissipation rate is compared to that of an equivalent solid one. The parameters considered axe geometrical dimensions and thermal properties of the fin and the perforations. The gain in the heat transfer enhancement and the fin weight reduction due to the perforations are considered. The study shows that the heat dissipation from the perforated fin for a certain range of triangular perforation di- mensions and spaces between perforations result in improvement in the heat transfer over the equivalent solid fin. The heat transfer enhancement of the perforated fin increases as the fin thermal conductivity and its thickness are increased.
Directory of Open Access Journals (Sweden)
Lotfi Said
2015-09-01
Full Text Available Purpose: This study has for objective the assessment of the vigilance, mood states variations and the blood glucose levels, during a triangular effort progressive in trained athletes during Ramadan fasting (RF. Methods. Ten trained male athletes aged 21.8 ± 1.1 years are evaluated before (B.RF, during (1st, 2nd and 3th week and after Ramadan fasting, in the blood-glucose, vigilance, and mood states at rest and after (A. Ex. a triangular exercise test (TUB II.Results. Comparing to the reference period (B.RF, the RF induces a decrease in the maximal aerobic power (TUB II approximately 2-Cleanup Messy Code 5% and a hypoglycaemia. The objective vigilance is doubly influenced by the RF (F= 14.58, p
Lee, Taejin
2016-09-01
We study the dissipative Hofstadter model on a triangular lattice, making use of the O(2, 2; R) T-dual transformation of string theory. The O(2, 2; R) dual transformation transcribes the model in a commutative basis into the model in a noncommutative basis. In the zero-temperature limit, the model exhibits an exact duality, which identifies equivalent points on the two-dimensional parameter space of the model. The exact duality also defines magic circles on the parameter space, where the model can be mapped onto the boundary sine-Gordon on a triangular lattice. The model describes the junction of three quantum wires in a uniform magnetic field background. An explicit expression of the equivalence relation, which identifies the points on the two-dimensional parameter space of the model by the exact duality, is obtained. It may help us to understand the structure of the phase diagram of the model.
Bello, Nakone; Singh, Jagadish
2016-01-01
We consider a version of the relativistic R3BP which includes the effects of oblateness of the primaries and radiation of the bigger primary as well on the stability of triangular points. We observe that the positions of the triangular points and their stability are affected by the relativistic effect apart from the radiation and oblateness of the primaries. It is further seen for these points that the range of stability region increases or decreases according as the part of the critical mass value, depending upon relativistic terms, radiation and oblateness coefficients, is positive or negative. A numerical exploration shows that in the Sun-Saturn, Sun-Uranus, Sun-Neptune systems, the oblateness has no influence on their positions and range of stability region; whereas it has a little influence on the Sun-Mars, Sun-Jupiter systems. On the other hand, we found that radiation pressure has an observable effect on the solar system.
Xue, Hong; You, Wen; Nayga, Rodolfo M.
2011-01-01
This essay investigates the impacts of primary care giver’s (PCG) time allocation and food expenditure choices on childhood obesity using national panel study of income dynamic (PSID) data. A triangular system of equations is derived and estimated under parametric and semi-parametric model settings. The performances of the two modeling strategies are compared using predictive ability measures with the aid of bootstrap method. Test results suggest relatively better performance of the semi-para...
Rycerz, Adam
2013-01-01
We investigate the effect of strain-induced gauge fields on statistical distribution of energy levels of triangular graphene nanoflakes with zigzag edges. In the absence of strain fields but in the presence of weak potential disorder such systems were found in Ref. [1] to display the spectral statistics of the Gaussian unitary ensemble (GUE) due to the effective time-reversal (symplectic) symmetry breaking. Here show that, in the absence of disorder, strain fields may solely lead to spectral ...
Iungo, Giacomo Valerio; Lombardi, Edoardo
2011-01-01
Time–frequency analysis of the dynamics of different wake vorticity structures, generated from a triangular prism orientated with its apex edge against the incoming wind, is carried out. Time–frequency analysis of time-series obtained with hot-wire anemometry is performed through a procedure based on proper orthogonal decomposition and spectral components are extracted with a technique that provides an increased efficiency for fluid dynamic applications.
A topological semimetal model with f-wave symmetry in a non-Abelian triangular optical lattice
Li, Ling; Bai, Zhiming; Hao, Ningning; Liu, Guocai
2016-08-01
We demonstrate that an chiral f-wave topological semimetal can be induced in a non-Abelian triangular optical lattice. We show that the f-wave symmetry topological semimetal is characterized by the topological invariant, i.e., the winding number W, with W=3 and is different from the semimetal with W=1 and 2 which have the p-wave and d-wave symmetry, respectively.
Asl, Rahim Taghizadeh; Eshrati, Babak; Dell Colleen Anne; Taylor, Kelli; Afshar, Parviz; Kamali, Mohammad; Mirzazadeh, Ali
2013-01-01
Background Transmission of the human immunodeficiency virus (HIV) among incarcerated injection drug users (IDU) is a health epidemic in the Islamic Republic of Iran. Triangular clinics (TCs) were established in prisons as a harm reduction measure to decrease the risk of HIV transmission and other blood-borne infections. The objective of this study was to assess the immediate outcomes of one TC among male IDUs in Iran’s Rajaee-Shahr prison. Methods This study was conducted in two stages betwee...
Layered Atom Arrangements in Complex Materials
Energy Technology Data Exchange (ETDEWEB)
K.E. Sikafus; R.W.Grimes; S.M.Corish; A.R. Cleave; M.Tang; C.R.Stanek; B.P. Uberuaga; J.A.Valdez
2005-04-15
In this report, we develop an atom layer stacking model to describe systematically the crystal structures of complex materials. To illustrate the concepts, we consider a sequence of oxide compounds in which the metal cations progress in oxidation state from monovalent (M{sup 1+}) to tetravalent (M{sup 4+}). We use concepts relating to geometric subdivisions of a triangular atom net to describe the layered atom patterns in these compounds (concepts originally proposed by Shuichi Iida). We demonstrate that as a function of increasing oxidation state (from M{sup 1+} to M{sup 4+}), the layer stacking motifs used to generate each successive structure (specifically, motifs along a 3 symmetry axis), progress through the following sequence: MMO, MO, M{sub r}O, MO{sub r/s}O{sub u/v}, MOO (where M and O represent fully dense triangular atom nets and r/s and u/v are fractions used to describe partially filled triangular atom nets). We also develop complete crystallographic descriptions for the compounds in our oxidation sequence using trigonal space group R{bar 3}.
Facile synthesis of MoS2 and MoxW1-xS2 triangular monolayers
Directory of Open Access Journals (Sweden)
Zhong Lin
2014-09-01
Full Text Available Single- and few-layered transition metal dichalcogenides, such as MoS2 and WS2, are emerging two-dimensional materials exhibiting numerous and unusual physico-chemical properties that could be advantageous in the fabrication of unprecedented optoelectronic devices. Here we report a novel and alternative route to synthesize triangular monocrystals of MoS2 and MoxW1-xS2 by annealing MoS2 and MoS2/WO3 precursors, respectively, in the presence of sulfur vapor. In particular, the MoxW1-xS2 triangular monolayers show gradual concentration profiles of W and Mo whereby Mo concentrates in the islands’ center and W is more abundant on the outskirts of the triangular monocrystals. These observations were confirmed by atomic force microscopy, and high-resolution transmission electron microscopy, as well as Raman and photoluminescence spectroscopy. The presence of tunable PL signals depending on the MoxW1-xS2 stoichiometries in 2D monocrystals opens up a wide range of applications in electronics and optoelectronics.
Directory of Open Access Journals (Sweden)
Jing Liu
2015-05-01
Full Text Available In this study, the nanosphere lithography (NSL method was used to fabricate hybrid Au-Ag triangular periodic nanoparticle arrays. The Au-Ag triangular periodic arrays were grown on different substrates, and the effect of the refractive index of substrates on fabrication and optical properties was systematically investigated. At first, the optical spectrum was simulated by the discrete dipole approximation (DDA numerical method as a function of refractive indexes of substrates and mediums. Simulation results showed that as the substrates had the refractive indexes of 1.43 (quartz and 1.68 (SF5 glass, the nanoparticle arrays would have better refractive index sensitivity (RIS and figure of merit (FOM. Simulation results also showed that the peak wavelength of the extinction spectra had a red shift when the medium’s refractive index n increased. The experimental results also demonstrated that when refractive indexes of substrates were 1.43 and 1.68, the nanoparticle arrays and substrate had better adhesive ability. Meanwhile, we found the nanoparticles formed a large-scale monolayer array with the hexagonally close-packed structure. Finally, the hybrid Au-Ag triangular nanoparticle arrays were fabricated on quartz and SF5 glass substrates and their experiment extinction spectra were compared with the simulated results.
Directory of Open Access Journals (Sweden)
Oronzio Manca
2015-01-01
Full Text Available In this paper, results obtained by the numerical investigation on laminar mixed convection in triangular ducts, filled with nanofluids, are presented in order to evaluate the fluid dynamic and thermal features of the considered geometry by considering Al2O3/water based nanofluids. The system is heated by a constant and uniform heat flux also along the perimeter of the triangular duct section in H2 mode as thermal boundary condition and the single-phase model has been assigned for a Reynolds number value equal to 100. Results are given for different nanoparticle volume concentrations and Richardson number values ranging from 0% to 5% and from 0 to 5, respectively. Results, presented for the fully developed regime flow, show the enhancement of average convective heat transfer coefficients values for increasing values of Richardson number and particle fractions. However, wall shear stress and required pumping power profiles increase as expected. The PEC analysis showed that the use of nanofluids in mixed convection seems slightly convenient. It should be underlined that, at the moment, experimental data are not available to compare the numerical proposed model for mixed convection in horizontal triangular ducts with nanofluids.
Qin, Guang-You
2013-01-01
We study elliptic and triangular flow in the collisions of deuteron-gold nuclei at $\\sqrt{s_{\\rm NN}} = 200$ GeV at RHIC and of proton-lead nuclei at $\\sqrt{s_{\\rm NN}} = 5.02$ TeV at the LHC, utilizing (3+1)-dimensional ideal hydrodynamics for the dynamic evolution of the fireball and a Glauber-based Monte-Carlo model for simulating the fluctuating initial conditions. Sizable values of elliptic and triangular flow are obtained for both colliding systems, and the results are consistent with PHENIX, ATLAS and CMS measurements. For these studied centralities, we find that the elliptic flow in proton-lead collisions is smaller than deuteron-gold collisions, while the triangular flows are comparable in both colliding systems. Our results indicate that the observed collective anisotropic flow in deuteron-gold and proton-lead collisions may be obtained from relativistic hydrodynamic evolution of the fireball with initial state fluctuations.
Clean环中的几个上三角矩阵环%Several Upper Triangular Matrix Rings of Clean Rings
Institute of Scientific and Technical Information of China (English)
温立书
2013-01-01
Several upper triangular matrix rings of clean rings were studied.By the definition of a clean ring (with 1) is extended to any ring (not necessarily with 1),some results were proved:Let R be a clean ring,and let G be a group of order 2,then group ring RG is also a clean ring under some conditions.Several upper triangular matrix rings are strongly clean rings.Then several results of clean rings were extended; some upper triangular matrix rings are a strongly f-clean rings.%研究了clean环中的几个上三角矩阵环.通过将clean环的定义推广到任意环(不必有1),得到若R是clean环,G是阶为2的群,满足一定条件,群环RG也是clean环；证明了一些上三角矩阵环是强clean环.最后推广了一些结论,得到一些上三角矩阵环是强f-clean环.
Crkovska, J; Bravina, L; Johansson, B H Brusheim; Zabrodin, E; Eyyubova, G; Korotkikh, V L; Lokhtin, I P; Malinina, L V; Petrushanko, S V; Snigirev, A M
2016-01-01
Triangular flow v_3 of identified and inclusive particles in lead-lead collisions at sqrt{s_{NN}} = 2.76 TeV is studied as a function of centrality and transverse momentum within the HYDJET++ model. The model enables to investigate the influence of both hard processes and final-state interactions on the harmonics of particle anisotropic flow. Decays of resonances are found to increase the magnitude of the v_3(p_T)-distributions at p_T > 2 GeV/c and shift their maxima to higher transverse momenta. The p_T-integrated triangular flow, however, becomes slightly weakened for all centralities studied. The resonance decays also modify the spectra towards the number-of-constituent-quark (NCQ) scaling fulfillment for the triangular flow, whereas jets are the main source of the scaling violation at energies of Large Hadron Collider. Comparison with the corresponding spectra of elliptic flow reveals several similarities in v_3(p_T) and v_2(p_T) behavior. Obtained results are also confronted to the available experimental...
Jiang, Wen Jun; Wittek, Peter; Zhao, Li; Gao, Shi Chao
2014-01-01
Photoplethysmogram (PPG) signals acquired by smartphone cameras are weaker than those acquired by dedicated pulse oximeters. Furthermore, the signals have lower sampling rates, have notches in the waveform and are more severely affected by baseline drift, leading to specific morphological characteristics. This paper introduces a new feature, the inverted triangular area, to address these specific characteristics. The new feature enables real-time adaptive waveform detection using an algorithm of linear time complexity. It can also recognize notches in the waveform and it is inherently robust to baseline drift. An implementation of the algorithm on Android is available for free download. We collected data from 24 volunteers and compared our algorithm in peak detection with two competing algorithms designed for PPG signals, Incremental-Merge Segmentation (IMS) and Adaptive Thresholding (ADT). A sensitivity of 98.0% and a positive predictive value of 98.8% were obtained, which were 7.7% higher than the IMS algorithm in sensitivity, and 8.3% higher than the ADT algorithm in positive predictive value. The experimental results confirmed the applicability of the proposed method. PMID:25570674
Energy Technology Data Exchange (ETDEWEB)
Vicente, Pedro C.; Falcao, Antonio F. de O.; Gato, Luiz M.C. [IDMEC, Instituto Superior Tecnico, Technical University of Lisbon, 1049-001 Lisboa (Portugal); Justino, Paulo A.P. [Laboratorio Nacional de Energia e Geologia, 1649-038 Lisboa (Portugal)
2009-07-01
It may be convenient that dense arrays of floating point absorbers are spread-moored to the sea bottom through only some of their elements (possibly located in the periphery), while the other array elements are prevented from drifting and colliding with each other by connections to adjacent elements. An array of identical floating point absorbers located at the grid points of an equilateral triangular grid is considered in the paper. A spread set of slack-mooring lines connect the peripheric floaters to the bottom. A weight is located at the centre of each triangle whose function is o pull the three floaters towards each other and keep the inter-body moorings lines under tension. The whole system - buoys, moorings and power take-off systems - is assumed linear, so that a frequency domain analysis may be employed. Hydrodynamic interference between the oscillating bodies is neglected. Equations are presented for a set of three identical point absorbers. This is then extended to more complex equilateral iriangular grid arrays. Results from numerical simulations, with regular and irregular waves, are presented for the motions and power absorption of hemispherical converters in arrays of three and seven elements and different mooring and power take-off parameters, and wave incidence angles. Comparisons are given with the unmoored and independently-moored buoy situations.
Zhang, Ling Ling; Ma, Fang Fang; Kuang, Yang Fang; Cheng, Shu; Long, Yun Fei; Xiao, Qiu Guo
2016-02-01
A simple, fast and highly sensitive spectrophotometric method for the determination of bovine serum albumin (BSA) has been developed based on the interactions between triangular silver nanoplates (TAgNPs) and BSA in the presence of Britton-Robison buffer solution (BR). Particularly, the wavelength of absorption maximum (λmax) of TAgNPs is red shifted in the presence of BSA together with Britton-Robinson buffer solution (BR, pH = 2.56), and the color of the solution changed from blue to light blue. This may be due to the interactions between BSA molecules on the surface of TAgNPs through electrostatic forces, hydrogen bonds, hydrophobic effects and van der Waals forces at pH 2.56, which leads to the aggregation of TAgNPs. The determination of BSA was achieved by measuring the change of λmax corresponding to localized surface plasmon resonance (LSPR) from UV-visible spectrophotometry. It was found that the shift value in the wavelength of absorption maximum (Δλ, the difference in absorption maxima of the TAgNPs/BSA/BR mixture and the TAgNPs/BR mixture) was proportionate to the concentration of BSA in the range of 1.0 ng mL- 1 to 100.0 ng mL- 1 with the correlation coefficient of r = 0.9969. The detection limit (3 σ/k) for BSA was found to be as low as 0.5 ng mL- 1.
Kumar, Abhay; Prasad, M N V; Sytar, Oksana
2012-11-01
Talinum species have been used to investigate a variety of environmental problems for e.g. determination of metal pollution index and total petroleum hydrocarbons in roadside soils, stabilization and reclamation of heavy metals (HMs) in dump sites, removal of HMs from storm water-runoff and green roof leachates. Species of Talinum are popular leaf vegetables having nutrient antinutrient properties. In this study, Talinum triangulare (Jacq.) Willd (Ceylon spinach) grown hydroponically were exposed to different concentrations of lead (Pb) (0, 0.25, 0.5, 0.75, 1.0 and 1.25 mM) to investigate the biomarkers of toxicity and tolerance mechanisms. Relative water content, cell death, photosynthetic pigments, sulphoquinovosyldiacylglycerol (SQDG), anthocyanins, α-tocopherol, malondialdehyde (MDA), reactive oxygen species (ROS) glutathione (GSH and GSSG) and elemental analysis have been investigated. The results showed that Pb in roots and shoots gradually increased as the function of Pb exposure; however Pb concentration in leaves was below detectable level. Chlorophylls and SQDG contents increased at 0.25 mM of Pb treatment in comparison to control at all treated durations, thereafter decreased. Levels of carotenoid, anthocyanins, α-tocopherol, and lipid peroxidation increased in Pb treated plants compared to control. Water content, cells death and elemental analysis suggested the damage of transport system interfering with nutrient transport causing cell death. The present study also explained that Pb imposed indirect oxidative stress in leaves is characterized by decreases in GSH/GSSG ratio with increased doses of Pb treatment. Lead-induced oxidative stress was alleviated by carotenoids, anthocyanins, α-tocopherol and glutathione suggesting that these defense responses as potential biomarkers for detecting Pb toxicity. PMID:22722003
Spin liquid nature in the Heisenberg J1-J2 triangular antiferromagnet
Iqbal, Yasir; Hu, Wen-Jun; Thomale, Ronny; Poilblanc, Didier; Becca, Federico
2016-04-01
We investigate the spin-1/2 Heisenberg model on the triangular lattice in the presence of nearest-neighbor J1 and next-nearest-neighbor J2 antiferromagnetic couplings. Motivated by recent findings from density-matrix renormalization group (DMRG) claiming the existence of a gapped spin liquid with signatures of spontaneously broken lattice point group symmetry [Zhu and White, Phys. Rev. B 92, 041105 (2015), 10.1103/PhysRevB.92.041105 and Hu, Gong, Zhu, and Sheng, Phys. Rev. B 92, 140403 (2015), 10.1103/PhysRevB.92.140403], we employ the variational Monte Carlo (VMC) approach to analyze the model from an alternative perspective that considers both magnetically ordered and paramagnetic trial states. We find a quantum paramagnet in the regime 0.08 ≲J2/J1≲0.16 , framed by 120∘ coplanar (stripe collinear) antiferromagnetic order for smaller (larger) J2/J1 . By considering the optimization of spin-liquid wave functions of a different gauge group and lattice point group content as derived from Abrikosov mean-field theory, we obtain the gapless U(1 ) Dirac spin liquid as the energetically most preferable state in comparison to all symmetric or nematic gapped Z2 spin liquids so far advocated by DMRG. Moreover, by the application of few Lanczos iterations, we find the energy to be the same as the DMRG result within error bars. To further resolve the intriguing disagreement between VMC and DMRG, we complement our methodological approach by the pseudofermion functional renormalization group (PFFRG) to compare the spin structure factors for the paramagnetic regime calculated by VMC, DMRG, and PFFRG. This model promises to be an ideal test bed for future numerical refinements in tracking the long-range correlations in frustrated magnets.
Fluorescence Visualization of Hypersonic Flow Past Triangular and Rectangular Boundary-layer Trips
Danehy, Paul M.; Garcia, A. P.; Borg, Stephen E.; Dyakonov, Artem A.; Berry, Scott A.; Inman, Jennifer A.; Alderfer, David W.
2007-01-01
Planar laser-induced fluorescence (PLIF) flow visualization has been used to investigate the hypersonic flow of air over surface protrusions that are sized to force laminar-to-turbulent boundary layer transition. These trips were selected to simulate protruding Space Shuttle Orbiter heat shield gap-filler material. Experiments were performed in the NASA Langley Research Center 31-Inch Mach 10 Air Wind Tunnel, which is an electrically-heated, blowdown facility. Two-mm high by 8-mm wide triangular and rectangular trips were attached to a flat plate and were oriented at an angle of 45 degrees with respect to the oncoming flow. Upstream of these trips, nitric oxide (NO) was seeded into the boundary layer. PLIF visualization of this NO allowed observation of both laminar and turbulent boundary layer flow downstream of the trips for varying flow conditions as the flat plate angle of attack was varied. By varying the angle of attack, the Mach number above the boundary layer was varied between 4.2 and 9.8, according to analytical oblique-shock calculations. Computational Fluid Dynamics (CFD) simulations of the flowfield with a laminar boundary layer were also performed to better understand the flow environment. The PLIF images of the tripped boundary layer flow were compared to a case with no trip for which the flow remained laminar over the entire angle-of-attack range studied. Qualitative agreement is found between the present observed transition measurements and a previous experimental roughness-induced transition database determined by other means, which is used by the shuttle return-to-flight program.
Mun, Sungyong
2016-06-24
The design approaches for a three-zone simulated moving bed (SMB) chromatography with linear isotherms can be classified into two categories, depending on whether the SMB design is based on a classical region (i.e., triangular region of the triangle theory) in the first quadrant (m2, m3) plane or on a non-triangular separation region in the third quadrant (m2, m3) plane. The SMBs based on the classical and the non-triangular design approaches, which are named here as (m(+))_SMB and (m(-))_SMB respectively, are compared in this study using the Pareto solutions from the simultaneous optimization of throughput and desorbent usage under the constraints on product purities and pressure drop. The results showed that the (m(-))_SMB approach led to significantly lower desorbent usage than the (m(+))_SMB approach, which was due to the fact that the flow-rate-ratios from the (m(-))_SMB approach are extremely lower than those from the (m(+))_SMB approach. This factor also enables the (m(-))_SMB to have a significantly lower pressure drop, thereby making its throughput less restricted by a pressure-drop constraint. Due to such advantage of the (m(-))_SMB, it can make a further substantial improvement in throughput by modulating its adsorbent particle size properly. This issue was investigated using a model separation system containing succinic acid and acetic acid. It was confirmed that if the adsorbent particle size corresponding to the boundary between a mass-transfer limiting region and a pressure-drop limiting region is adopted, the (m(-))_SMB can lead to 82% higher throughput and 73% lower desorbent usage than the (m(+))_SMB. PMID:27208988
Das, M.; Barut, A.; Madenci, E.; Ambur, D. R.
2004-01-01
This study presents a new triangular finite element for modeling thick sandwich panels, subjected to thermo-mechanical loading, based on a {3,2}-order single-layer plate theory. A hybrid energy functional is employed in the derivation of the element because of a C interelement continuity requirement. The single-layer theory is based on five weighted-average field variables arising from the cubic and quadratic representations of the in-plane and transverse displacement fields, respectively. The variations of temperature and distributed loading acting on the top and bottom surfaces are non-uniform. The temperature varies linearly through the thickness.
Homma, Yuto; Moriwaki, Hiroyuki; Ohki, Shigeo; Ikeda, Kazumi
2014-06-01
This paper deals with verification of three dimensional triangular prismatic discrete ordinates transport calculation code ENSEMBLE-TRIZ by comparison with multi-group Monte Carlo calculation code GMVP in a large fast breeder reactor. The reactor is a 750 MWe electric power sodium cooled reactor. Nuclear characteristics are calculated at beginning of cycle of an initial core and at beginning and end of cycle of equilibrium core. According to the calculations, the differences between the two methodologies are smaller than 0.0002 Δk in the multi-plication factor, relatively about 1% in the control rod reactivity, and 1% in the sodium void reactivity.
Energy Technology Data Exchange (ETDEWEB)
Fakori-Monazah, M.R.; Todreas, N.E.
1977-08-01
A simulated model of triangular array rods with pitch to diameter ratio of 1.10 (as a test section) and air as the fluid flow was used to study the LMFBR hydraulic parameters. The wall shear stress distribution around the rod periphery, friction factors, static pressure distributions and turbulence intensity corresponding to various Reynolds numbers ranging from 4140 to 36170 in the central subchannel were measured. Various approaches for measurement of wall shear stress were compared. The measurement was performed using the Preston tube technique with the probe outside diameter equal to 0.014 in.
Directory of Open Access Journals (Sweden)
R.S. Khymyn
2014-09-01
Full Text Available The regular array of magnetic particles (magnetic dots of the form of a two-dimensional triangular lattice in the presence of external magnetic field demonstrates complicated magnetic structures. The magnetic symmetry of the ground state for such a system is lower than that for the underlying lattice. Long range dipole-dipole interaction leads to a specific antiferromagnetic order in small fields, whereas a set of linear topological defects appears with the growth of the magnetic field. Self-organization of such defects determines the magnetization process for a system within a wide range of external magnetic fields.
Design of triangular core LMA-PCF with low-bending loss and low non-linearity for laser application
Kabir, Sumaiya; Khandokar, Md. Rezwanul Haque; Khan, Muhammad Abdul Goffar
2016-07-01
In this paper we characterize the design of a simple large-mode area photonic crystal fiber (LMA-PCF) with low bending loss and low non-linearity. The finite element method (FEM) with perfectly matched boundary layer (PML) is used to investigate the guiding properties. According to simulation the characterized four ring fluorine doped triangular core LMA-PCF achieves 1500 μm2 effective mode area with a low bending loss of 10-5dB/km at the wavelength of 1.064 μm and at a bending radius of 40 cm which is suitable for high power fiber laser.
Institute of Scientific and Technical Information of China (English)
WANG Hui-feng; DU Hong-bin
2008-01-01
In this paper,a neural-network-based variable structure control scheme is presented for a class of nonlinear systems with a general low triangular structure.The proposed variable structure controller is proved to be C1,thus can be applied for backstepping design,which has extended the scope of previous nonlinear systems in the form of strict-feedback and pure-feedback.With the help of neural network approximator,H-oo performance analysis of stability is given.The effectiveness of proposed control law is verified via simulation.
Janani, C.; Merino, J.; McCulloch, I. P.; Powell, B. J.
2014-01-01
Motivated by Mo$_3$S$_7$(dmit)$_3$, we investigate the Hubbard model on the triangular necklace lattice at two-thirds filling. We show, using second order perturbation theory, that in the molecular limit, the ground state and the low energy excitations of this model are identical to those of the spin-one Heisenberg chain. The latter model is known to be in the symmetry protected topological Haldane phase. Away from this limit we show, on the basis of symmetry arguments and density matrix reno...
Institute of Scientific and Technical Information of China (English)
Niphon Wansophark; Pramote Dechaumphai
2008-01-01
A streamline upwind finite element method using 6-node triangular element is presented.The method is applied to the convection term of the governing transport equation directly along local streamlines.Several convective-diffusion examples are used to evaluate efficiency of the method.Results show that the method is monotonic and does not produce any oscillation.In addition,an adaptive meshing technique is combined with the method to further increase accuracy of the solution,and at the same time,to minimize computational time and computer memory requirement.
Bryson, Steve
2010-10-11
We introduce a new second-order central-upwind scheme for the Saint-Venant system of shallow water equations on triangular grids. We prove that the scheme both preserves "lake at rest" steady states and guarantees the positivity of the computed fluid depth. Moreover, it can be applied to models with discontinuous bottom topography and irregular channel widths. We demonstrate these features of the new scheme, as well as its high resolution and robustness in a number of numerical examples. © EDP Sciences, SMAI, 2010.
Effect of bismuth surfactant on InP-based highly strained InAs/InGaAs triangular quantum wells
Energy Technology Data Exchange (ETDEWEB)
Gu, Y.; Zhang, Y. G., E-mail: ygzhang@mail.sim.ac.cn; Chen, X. Y.; Xi, S. P.; Du, B.; Ma, Y. J. [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)
2015-11-23
We report the effect of Bi surfactant on the properties of highly strained InAs/InGaAs triangular quantum wells grown on InP substrates. Reduced surface roughness, improved heterostructure interfaces and enhanced photoluminescence intensity at 2.2 μm are observed by moderate Bi-mediated growth. The nonradiative processes are analysed based on temperature-dependent photoluminescence. It is confirmed that Bi incorporation is insignificant in the samples, whereas excessive Bi flux during the growth results in deteriorated performance. The surfactant effect of Bi is promising to improve InP-based highly strained structures while the excess of Bi flux needs to be avoided.
Behroozi, F.; Behroozi, P. S.
2011-09-01
A chain assumes the well-known shape known as a catenary when it hangs loosely from two points in a gravitational field. The correct solution of the catenary was one of the early triumphs of the newly invented calculus of variations at the end of the 17th century. Here we revisit the catenary and show that, for a chain hanging from a horizontal rod, three new and distinct configurations are possible if a soap film covers the area bounded by the chain and the rod. We first review the general problem and discuss the conditions under which the chain assumes a concave, triangular or convex configuration. The deciding factor is the strength of surface tension relative to the gravitational force per unit length of the chain. The conditions under which the chain assumes the shape of a perfect triangle are discussed in greater detail and analysed to obtain the tension along the chain. The triangular configuration is especially intriguing to undergraduates and may be used as a simple experiment to obtain the surface tension of the soap solution by measuring just one angle of the triangle.
Directory of Open Access Journals (Sweden)
Sylvain Druart
2014-01-01
Full Text Available We present a methodology and a circuit to extract liquid resistance and capacitance simultaneously from the same output signal using interdigitated sensing electrodes. The principle consists in the generation of a current square wave and its application to the sensor to create a triangular output voltage which contains both the conductivity and permittivity parameters in a single periodic segment. This concept extends the Triangular Waveform Voltage (TWV signal generation technique and is implemented by a system which consists in a closed-loop current-controlled oscillator and only requires DC power to operate. The system interface is portable and only a small number of electrical components are used to generate the expected signal. Conductivities of saline NaCl and KCl solutions, being first calibrated by commercial equipment, are characterized by a system prototype. The results show excellent linearity and prove the repeatability of the measurements. Experiments on water-glycerol mixtures validate the proposed sensing approach to measure the permittivity and the conductivity simultaneously. We discussed and identified the sources of measurement errors as circuit parasitic capacitances, switching clock feedthrough, charge injection, bandwidth, and control-current quality.
Spin frustration and magnetic ordering in triangular lattice antiferromagnet Ca3CoNb2O9
Dai, Jia; Zhou, Ping; Wang, Peng-Shuai; Pang, Fei; Munsie, Tim J.; Luke, Graeme M.; Zhang, Jin-Shan; Yu, Wei-Qiang
2015-12-01
We synthesized a quasi-two-dimensional distorted triangular lattice antiferromagnet Ca3CoNb2O9, in which the effective spin of Co2+ is 1/2 at low temperatures, whose magnetic properties were studied by dc susceptibility and magnetization techniques. The x-ray diffraction confirms the quality of our powder samples. The large Weiss constant θCW˜ -55 K and the low Neel temperature TN˜ 1.45 K give a frustration factor f = | θCW/TN | ≈ 38, suggesting that Ca3CoNb2O9 resides in strong frustration regime. Slightly below TN, deviation between the susceptibility data under zero-field cooling (ZFC) and field cooling (FC) is observed. A new magnetic state with 1/3 of the saturate magnetization Ms is suggested in the magnetization curve at 0.46 K. Our study indicates that Ca3CoNb2O9 is an interesting material to investigate magnetism in triangular lattice antiferromagnets with weak anisotropy. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374364 and 11222433), the National Basic Research Program of China (Grant No. 2011CBA00112). Research at McMaster University supported by the Natural Sciences and Engineering Research Council. Work at North China Electric Power University supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry.
On the peculiar properties of triangular-chain EuCr{sub 3}(BO{sub 3}){sub 4} antiferromagnet
Energy Technology Data Exchange (ETDEWEB)
Gondek, Ł., E-mail: lgondek@agh.edu.pl [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Szytuła, A. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków (Poland); Przewoźnik, J.; Żukrowski, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Prokhorov, A.; Chernush, L.; Zubov, E. [A.A. Galkin Donetsk Physico-Technical Institute, NANU, 83114 Donetsk, R. Luxembourg str. 72 (Ukraine); Dyakonov, V. [A.A. Galkin Donetsk Physico-Technical Institute, NANU, 83114 Donetsk, R. Luxembourg str. 72 (Ukraine); Institute of Physics, PAS, 02-668 Warsaw, Al. Lotników 32/46 (Poland); Duraj, R. [Institute of Physics Technical University of Cracow, Podchorazych 1, 30-084 Krakow (Poland); Tyvanchuk, Yu. [Analytical Chemistry Department, Ivan Franko National University of Lviv, Kyryla and Mephodiya 6, 79005 Lviv (Ukraine)
2014-02-15
In this paper we report studies on EuCr{sub 3}(BO{sub 3}){sub 4} compound, that is a member of newly discovered family of huntite-related specimens for non-linear optics. For the first time, the uncommon temperature dependence of the EuCr{sub 3}(BO{sub 3}){sub 4} lattice parameters is reported. Additionally, the magnetism of this compound is extremely interesting. Namely, a possible interplay in between potentially magnetic rare-earth ions and 3d metal stacked within quasi-1D chain that can lead to a great variety of magnetic behaviour. Indeed, in our studies we have found 3D-long range ordering with metamagnetic behaviour, while at higher temperature the magnetic chains become uncoupled. - Graphical abstract: Torsion-like vibrations are the key to understand negative thermal expansion along the a-axis. Display Omitted - Highlights: • EuCr{sub 3}(BO{sub 3}){sub 4} is a peculiar triangular-chain antiferromagnet. • Rare earth sublattice is non-magnetic with Eu{sup 3+} configuration. • Cr{sup 3+} magnetic moments show 1-D behaviour along with spin fluctuations. • Torsion vibrations of Cr triangular tubes lead to anomalous expansion of unit cell.
Kapania, R. K.; Mohan, P.
1996-09-01
Finite element static, free vibration and thermal analysis of thin laminated plates and shells using a three noded triangular flat shell element is presented. The flat shell element is a combination of the Discrete Kirchhoff Theory (DKT) plate bending element and a membrane element derived from the Linear Strain Triangular (LST) element with a total of 18 degrees of freedom (3 translations and 3 rotations per node). Explicit formulations are used for the membrane, bending and membrane-bending coupling stiffness matrices and the thermal load vector. Due to a strong analogy between the induced strain caused by the thermal field and the strain induced in a structure due to an electric field the present formulation is readily applicable for the analysis of structures excited by surface bonded or embedded piezoelectric actuators. The results are presented for (i) static analysis of (a) simply supported square plates under doubly sinusoidal load and uniformly distributed load (b) simply supported spherical shells under a uniformly distributed load, (ii) free vibration analysis of (a) square cantilever plates, (b) skew cantilever plates and (c) simply supported spherical shells; (iii) Thermal deformation analysis of (a) simply supported square plates, (b) simply supported-clamped square plate and (c) simply supported spherical shells. A numerical example is also presented demonstrating the application of the present formulation to analyse a symmetrically laminated graphite/epoxy laminate excited by a layer of piezoelectric polyvinylidene flouride (PVDF). The results presented are in good agreement with those available in the literature.
Energy Technology Data Exchange (ETDEWEB)
Duque, C.A., E-mail: cduque@fisica.udea.edu.co [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia); Mora-Ramos, M.E. [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia); Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos, México (Mexico); Kasapoglu, E.; Ungan, F.; Yesilgul, U. [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Sakiroglu, S. [Dokuz Eylül University, Physics Department, 35160 Buca, İzmir (Turkey); Sari, H. [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Sökmen, I. [Dokuz Eylül University, Physics Department, 35160 Buca, İzmir (Turkey)
2013-11-15
The 1s-like and 2p-like donor impurity energy states are studied in a semiconductor quantum wire of equilateral triangular cross section as functions of the impurity position and the geometrical size of the structure. Linear and nonlinear coefficients for the optical absorption and relative refractive index change associated with 1s→2p transitions are calculated for both the x-polarization and y-polarization of the incident light. The results show a mixed effect of redshift and blueshift depending on the location of the donor atom. Also, strong nonlinear contributions to the optical absorption coefficient are obtained for both polarizations in the on-center impurity case. -- Highlights: • The 1s- and 2p-like impurity states in triangular quantum-well wires. • Optical absorption and relative refractive index changes are calculated. • Redshift and blueshift in the optical structures depend on the donor position. • Strong nonlinear contributions to the absorption coefficient have been obtained.
Ren, Jing; Liu, Yueqiang; Liu, Yue; Medvedev, S. Yu; Wang, Zhirui; Xia, Guoliang
2016-11-01
The effects of an ideal/resistive conducting wall, the drift kinetic resonances, as well as the toroidal plasma flow, on the stability of the ideal external kink mode are numerically investigated for a reactor-relevant tokamak plasma with strongly negative triangularity (NTR) shaping. Comparison is made for a similar plasma equilibrium, but with positive triangularity (PTR). It is found that the ideal wall stabilization is less efficient for the kink stabilization in the NTR plasma due to a less ‘external’ eigenmode structure compared to the PTR plasma. The associated plasma displacement in the NTR plasma does not ‘balloon’ near the outboard mid-plane, as is normally the case for the pressure-driven kink-ballooning instability in PTR plasmas, but being more pronounced near the X-points. The toroidal flow plays a similar role for the kink stability for both NTR and PTR plasmas. The drift kinetic damping is less efficient for the ideal external kink mode in the NTR plasma, despite a somewhat larger fraction of the particle trapping near the plasma edge compared to the PTR equilibrium. However, the drift kinetic damping of the resistive wall mode (RWM) in the NTR plasma is generally as efficient as that of the PTR plasma, although the RWM window, in terms of the normalized pressure, is narrower for the NTR plasma.
DEFF Research Database (Denmark)
Kanaya, Shin
higher-order moments. Several previous studies have presented various versions of laws of large numbers for sequences/triangular arrays, but their convergence rates were not fully investigated. This study is the first to investigate the convergence rates of the sums of α-mixing triangular arrays whose......The convergence rates of the sums of α-mixing (or strongly mixing) triangular arrays of heterogeneous random variables are derived. We pay particular attention to the case where central limit theorems may fail to hold, due to relatively strong time-series dependence and/or the non-existence of...... convergence theorems indicate that an explicit trade-off exists between the rate of convergence and the degree of dependence. While the results under the infill assumption can be seen as a direct extension of those under the fixed-distance assumption, they are new and particularly useful for deriving sharper...
Institute of Scientific and Technical Information of China (English)
Chen Zhao; Hu Chen Wei-Hua; Xiao-Dong; Yang Wei; Liu Lei; Wan Cheng-Hao; Li Lei; He Yong-Fa; Liu Ning-Yang; Wang Lei; Li Din
2012-01-01
The InGaN/GaN blue light emitting diode (LED) is numerically investigated using a triangular-shaped quantum well model,which involves analysis on its energy band,carrier concentration,overlap of electron and hole wave functions,radiative recombination rate,and internal quantum efficiency.The simulation results reveal that the InGaN/GaN blue light emitting diode with triangular quantum wells exhibits a higher radiative recombination rate than the conventional light emitting diode with rectangular quantum wells due to the enhanced overlap of electron and hole wave functions (above 90％) under the polarization field.Consequently,the efficiency droop is only 18％ in the light emitting diode with triangular-shaped quantum wells,which is three times lower than that in a conventional LED.
Masrour, R.; Jabar, A.
2016-07-01
Mixed-spin-1 and spin-3/2 Ising model on the decorated triangular lattice is studied by the use of Monte Carlo simulation. Within this approach, the results for the ground-state of the antiferromagnetic and ferromagnetic of decorated triangular lattice are obtained. The reduced transition temperature of each sublattice are obtained. The reduced temperature of compensation is also obtained. The thermal total ratio of magnetic susceptibilities of sublattices is given. The effect of crystal field and exchange interactions on the magnetization of the system are detailed. The magnetic hysteresis cycles are found for different values of exchanges interactions between the same lattice and the two sublattices different, for different crystal filed and temperatures. In addition, very weak exchange interactions and for a higher temperatures and a higher crystal filed values the decorated triangular lattice has been exhibited the superparamagnetic behavior.
Variable-weight Based Method for lntuitionistic Triangular Fuzzy Decision Making%三角直觉模糊决策的变权方法
Institute of Scientific and Technical Information of China (English)
余高锋; 李登峰; 邱锦明
2015-01-01
研究了属性值为三角直觉模糊数的多属性决策问题，提出了一种基于变权综合的决策方法。首先，针对三角直觉模糊数，提出一种新的三角直觉模糊排序方法；其次，定义了三角直觉模糊变权加权算术平均算子和三角直觉模糊变权加权几何平均算子；然后，提出一种基于三角直觉模糊变权集成算子的多属性决策方法；最后，数值算例说明了该方法的有效性。%For multi-attribute decision making problems where the attribute values are intuitionistic triangular fuzzy numbers, a new decision making method is developed on the basis of variable-weight vector.Firstly, the concept of triangular intuitionistic fuzzy numbers is introduced, and a new ranking method of triangular intuition-istic fuzzy numbers is presented.Secondly, the triangular intuitionistic fuzzy variable-weight weighted averaging operator and triangular intuitionistic fuzzy variable-weight weighted geometric averaging operator are proposed. Then, a method for multiple attribute decision making based on triangular intuitionistic fuzzy variable-weight aggregation operators is developed.Finally, an illustrative example shows the effectiveness of the proposed approach.