4,632 research outputs found
Thermo-mechanical analysis of periodic multiphase materials by a multiscale asymptotic homogenization approach
No full textA spatial and temporal multiscale asymptotic homogenization method used to simulate thermo-dynamic wave propagation in periodic multiphase materials is systematically studied. A general field governing equation of thermo-dynamic wave propagation is expressed in a unified form with both inertia and velocity terms. Amplified spatial and reduced temporal scales are, respectively, introduced to account for spatial and temporal fluctuations and non-local effects in the homogenized solution due to material heterogeneity and diverse time scales. The model is derived from the higher-order homogenization theory with multiple spatial and temporal scales. It is also shown that the modified higher-order terms bring in a non-local dispersion effect of the microstructure of multiphase materials. One-dimensional non-Fourier heat conduction and dynamic problems under a thermal shock are computed to demonstrate the efficiency and validity of the developed procedure. The results indicate the disadvantages of classical spatial homogenization. Copyright (c) 2006 John Wiley & Sons, Lt
Interaction between different internal length scales in strain localization analysis of fully and partially saturated porous media - the 1-D case
No full textThe paper analyses the interaction between two internal length scales during dynamic strain localization in multiphase porous materials. The first internal length is introduced in the mathematical model by the gradient-dependent plasticity for the solid skeleton, while the second one is naturally contained in the multiphase model and is due to the seepage process of the water via Darcy's law, which induces a rate-dependent behaviour of the solid skeleton. Numerical results of a one-dimensional example of water saturated porous medium demonstrate the competing effect between these two length scales. The porous medium is here treated as a multiphase continuum, with the pores filled by water and air, the last one at constant atmospheric pressure
An internal length scale in dynamic strain localization of multiphase porous media
Get PDFIn this paper, a length scale included in multiphase materials such as saturated and partially saturated porous media is discussed, where the viscous terms are introduced naturally by the fluid mass balance equations. The discussion is limited to the dynamic case. The characteristic stability equation is given in explicit form for one-dimensional wave propagation. It is shown that for axial waves a wave number domain exists for which the material model is dispersive when softening behaviour occurs for solid skeleton and that an internal length scale can be derived, while for ideal shear propagation this is not the case. Numerical examples are given to corroborate the validity of the expressions derived
Strain localisation modelling in saturated sand samples
No full textDynamic strain localisation theory together with a multiphase material model is used to simulate shear band dominated processes in fully saturated undrained sand samples. In the case of dense sands a Mohr-Coulomb constitutive relationship with non-associative plasticity is used while the Pastor-Zienkiewicz material model is adopted for medium-loose sand samples. Pore pressure distributions which are typical for the two situations are shown
MASTERSYMMETRIES, ANGLE VARIABLES, AND RECURSION OPERATOR OF THE RELATIVISTIC TODA LATTICE
No full textA Shared Buffer Constrained Topology Reconfiguration Scheme in Wavelength Routed Networks
No full textSome theoretical aspects of strain localization analysis of multiphase porous media with regularized constitutive models
No full textThis paper discusses some theoretical aspects of strain localiza-
tion analysis in multiphase porous media, particularly when reg-
ularized constitutive models such as the gradient-dependent and
rate-dependent models are used. Stability and hyperbolicity of the governing equations are studied and the relations between permeability and the wave number where a real wave speed exists are investigated numerically. Particular attention is focused on the two cases of wave number K=0 and K→∞ of the perturbation waves.
The interaction between the different internal length scale parameters during dynamic strain localization in multiphase porous materials is also studied. It is pointed out that the consideration of fluid interaction is necessary for the prediction of the internal length in a multiphase porous medium when regularization through a constitutive model is introduced in the numerical model to overcome mesh dependence in a finite element solution
Yunnanosticta cyaneocollaris Dow & Zhang 2018, sp. nov.
No full textYunnanosticta cyaneocollaris sp. nov. (Figs 2, 4, 6, 8, 11, 13, 15, 17, 19, 21, 23, 24, 26) Drepanosticta sp. 4;— Zhang 2017: Fig. 24d (photograph of male in life). Holotype. ♂, Tongbiguan National Nature Reserve (24.5833 N, 97.5856 E, ca 1220 m), Yingjiang County, Dehong Dai & Jingpo Autonomous Prefecture, Yunnan, China, 23 vi 2015, leg. H.M. Zhang, to be deposited in BMNH. Paratypes. 1 ♂, Tongbiguan National Nature Reserve (24.6636 N, 97.5883 E, ca 740 m), Yingjiang County, Dehong Dai & Jingpo Autonomous Prefecture, Yunnan, China, 0 6 vii 2014, leg. H.M. Zhang, in the collection of the H.M. Zhang. Etymology. The species is named cyaneocollaris, a noun in apposition: meaning “blue neck”, in reference to the largely blue prothorax. Description of holotype. Head (Fig. 2). Labium pale brown. Labrum whitish in basal ca two-thirds, dark brown below. Mandible bases very dark brown, whitish in corner adjacent to labrum and clypeus. Anteclypeus whitish, postclypeus shining black. Genae dark brown, frons obscurely brown and black. Vertex, occiput black, small whitish sub triangular marking at front median ocellus, small whitish marks at outer sides lateral ocelli. Underside of head shining black. Ratio of width of compound eye to width of vertex measured at level of lateral ocelli ca 0.6. Transverse occipital carina not very prominent. Ocelli whitish. Antenna with scape mostly pale, pedicel greyish, hardly narrower than scape, slightly expanded apically, rest missing. Thorax. Prothorax (Figs 4, 6) with anterior pronotal lobe black, propleuron yellow, narrowly dark brown at rear, middle pronotal lobe mottled blue and yellow, posterior pronotal lobe blue, narrowly framed in black. Anterior pronotal lobe with anterior carina same height as highest part of raised part. Posterior pronotal lobe short, simple, collar-like. Synthorax (Fig. 8) entirely brown, including venter, with small blue marks just below interpleural suture, near antealar carina on metepisternum, Venter of synthorax dark brown. Legs (middle right leg absent below trochanter): almost entirely yellowish, brown mark rear of coxae on middle and posterior pairs, narrowly dark around joint of femur and tibia, with faint, partial, poorly defined greyish ring around femur at ca two-thirds of its length. Wings: 15 Px in Fw, 14 Px in Hw. Vein Ab present, joined to Ac to form Y, single postcubital vein present in all wings. Arculus arising at or slightly distal to Ax2. R4 arising proximal to subnodus, IR3 distal to subnodus, joined to R4 by short stalk. CuP meeting wing margin at ca level of Px 6 in Fw, Px 9 in Hw; R4 meets the wing margin just beyond level of distal end of Pt. R3 arises at ca level of Px 6 in Fw, Px 5 in Hw, IR2 ca 1 Px further distal except in left Hw where 2 Px further distal. Both R3 and IR2 meet the wing margin at the falcate tip. Pterostigma almost rhomboidal, black with narrow pale border, covering one underlying cell. Abdomen. S1 brown. S2 brown with narrow transverse pale dorsal basal mark. S3–7 largely brown, becoming darker apically and on successive segments, with pale dorsal basal mark, separated from diffuse sub basal pale mark along lower margin of tergite, dorsal mark becoming fainter on successive segments, sub basal mark longer. S8 similar but dorsal basal marking very small, irregular (Figs 15, 17), pale blue dorsal marking in apical ca two thirds (Fig. 17). S9 pale blue except black lower laterally, S10 black with tiny, faint blue mark on left side dorsally (Fig. 17). Anal appendages (Figs 19, 21, 23) dark brown and black. Cerci short, simple, in lateral view (Fig. 19) narrowing gradually from base to rounded apex, curved gently up then down to apex, a strong but narrow ventral tooth present; in dorsal (Fig. 21) view bulbous, subcircular, apex broad and slightly, very shallowly bifurcated. Paraprocts a little longer than cerci (Fig. 19), in lateral view subtriangular for most of their length, bifurcated at apex into rounded outer branch, best seen in ventral view (Fig. 23) and with up turned inner branch, best seen in lateral view (Fig. 19); in ventral view the inner branch appearing short, pointed. Note that in Figure 21 the difference in length between cerci and paraprocts appears greater than it really is, this is because of the angle from which the drawing was made. Genital ligula (Figs 11, 13). Terminal segment narrower than penultimate segment, relatively short, apically divided into two arms lying on either side of shaft, expanded apically and curved forward (Fig. 11). Internal fold very large. Measurements (mm). Abdomen without anal appendages ca 25, cercus ca 0.3, Hw ca 16.5. Female. Unknown. Variation in paratype male. No significant variation was found in the single paratype, except that the blue dorsal mark on S8 extends almost the entire length of the segment (see Fig. 26). Diagnosis. The male is easily separated from all other known members of the Platystictidae except Y. wilsoni by the characters defining the genus. It is separated from Y. wilsoni by the dark venter of the synthorax, the very large internal fold and differently shaped terminal arms of the genital ligula, the cerci slightly shorter than the paraprocts, the subapical tooth on the cercus positioned ventrally and longer than in Y. cyaneocollaris, and the shorter inner branch of the paraproct. Remarks. The habitats of this species are seepages and narrow streams in the shade. The holotype male was collected at the same locality as that of Y. wilsoni. The paratype male was collected at a lower altitude of ca 740m, where it was perching on a leaf at a stream margin. The stream is in shady forest, about 0.5m in width and rather shallow, the substrate is silver sand. Except for two paratype males of Y. wilsoni, no other species was found at this location. This species appears to occur at very low densities.Published as part of Dow, Rory A. & Zhang, Hao-Miao, 2018, Yunnanosticta gen. nov., from Yunnan, a new genus from the Sinostictinae, with the description of two new species (Odonata: Zygoptera: Platystictidae), pp. 567-577 in Zootaxa 4375 (4) on pages 573-576, DOI: 10.11646/zootaxa.4375.4.6, http://zenodo.org/record/116100
Ooencyrtus protohermesis Zhang & Zhang, sp. n.
No full textOoencyrtus protohermesis Zhang & Zhang, sp. n. (Figs 22 –30, 37) Holotype. female, China: Beijing, Huairou, 7.VII. 2013, Ex. Protohermes xanthodes, Coll. FQ Chen (IZCAS). Paratypes: 22 females, data same as holotype. Description. Female (Holotype): length excluding ovipositor 1.0 mm (Fig. 37). Head dark brown with slight green sheen; pronotum and mesonotum dark brown with purplish sheen; posterior half of scutellum with a metallic green sheen; mesopleuron yellow; propodeum pale brown; antenna with scape yellow-brown; pedicel and flagellum pale brown; maxillary and labial palpi yellow; wings hyaline; legs mostly yellow except hind femur dark brown (Fig. 29); metasoma with slightly purplish sheen; ovipositor sheath yellow. Head. Frontovertex with fairly regular polygonal reticulate sculpture; eyes clothed in very fine, inconspicuous setae and slightly overreaching occipital margin which is sharp; ocelli forming acute angle about 70 °; scrobe deep; torulus located midway between lowest eye margin and clypeus, separated from each other by about 1.5 × own diameter; antenna with scape cylindrical, about 3.6 × as long as broad; pedicel subtriangular, 2 × as long as broad; funiculars transverse, F 1 –F 4 subequal in length, F 2 –F 4 subequal in width, F 5 –F 6 gradually broader, ratio of width and length of each segment: 1.5, 2, 2, 2, 1.7, 2; clava 3 -segmented, about as long as F 1 –F 6 combined, wider than F 6, apex with short slightly oblique truncation (Fig. 22); mandible with three acute teeth (Fig. 24); maxillary and labial palpi 4 - and 3 -segmented respectively (Fig. 23). Mesosoma. Pronotum and mesonotum clothed with sparse black setae, with shallow imbricate-reticulate sculpture except apex of scutellum smooth, with 2 or 3 long setae; mesopleuron more or less enlarged but not reaching metasoma so that metapleuron not visible laterally and propodeum slightly separated from base of hind coxa; fore wing (Fig. 25) about 2.5 × as long as wide; costal cell with more than one line of setae dorsally; linea calva more or less closed by a single line of setae dorsally; marginal vein about as long as stigmal vein; postmarginal vein about four-fifths as long as marginal vein. Metasoma. Longer than mesosoma; hypopygium reaching slightly more than two-thirds length of metasoma; ovipositor clearly exserted (Fig. 30), relative proportion of OL and MT: 63: 35. Relative measurements. HW 48, HL 39, FV 17, FVL 25, POL 6, AOL 4, OOL 1, OCL 2, POD 4, AOD 4, EL 25, EW 17, MS 5, SL 18, SW 5, PL 8, PW 4, CL 14, CW 7, FWL 131, FWW 53, HWL 85, HWW 19, MT 35, MTS 10, OL 63, GL 20. Male. Unknown. Host. Protohermes xanthodes Navás (Megaloptera: Corydalidae). Distribution. China (Beijing). Etymology. The specific epithet of this new species refers to its host.Published as part of Zhang, Xu, Zhang, Yan-Zhou, Wang, Ying, Chen, Fu-Qiang, Yu, Fang & Zhou, Qing-Song, 2014, Description of three new species of Ooencyrtus (Hymenoptera: Encyrtidae) from China, pp. 451-465 in Zootaxa 3790 (3) on pages 459-462, DOI: 10.11646/zootaxa.3790.3.4, http://zenodo.org/record/22656
Coccophagus bandus Zhang & Hu & Zhang 2023, sp. nov.
No full text<i>Coccophagus bandus</i> Zhang & Zhang, sp. nov. <p>(Figs. 1–12)</p> <p> <b>Type material.</b> Holotype. ♀ [on slide], CHINA, Qinghai, Xining, 22.VI.2007, XB Wang and X Zhang (deposited in IZCAS), reared from <i>Rhodococcus sariuoni</i> Borchsenius on <i>Prunus persica</i> Batsch. Paratypes. 30♀, 12♁, same data as holotype (deposited in IZCAS).</p> <p> <b>Other material.</b> CHINA, 13♀, 5♁, Henan, Zhengzhou, 27.IV.2009, YZ Zhang, reared from <i>Rhodococcus sariuoni</i> Borchsenius <i>on</i> <i>Prunus cerasifera</i> Ehrhar; 31♀, Inner Mongolia, Baotou, 24. V.2013, XB Wang and X Zhang, reared from <i>Rhodococcus sariuoni</i> Borchsenius on <i>Malus micromalus</i> Makino; 54♀, 12♁, Qinghai, Xining, 26. V.2013, YZ Zhang, reared from <i>Rhodococcus sariuoni</i> Borchsenius <i>on</i> <i>Prunus cerasifera</i> Ehrhar; 2♀, Tibet, Lasa, 2. VI.2019, QT Wu, sweeping; 3♀, Yunnan, Wenshan, 22.IV.2022, XB Wang, reared from <i>Takahashia japonica</i> Cockerell on <i>Cerasus pseudocerasus</i> Lindl; 2♀, Tibet, Rikaze, 19. V.2022, HL Li and LW Zhang, reared from <i>Eulecanium kuwanai</i> Kanda <i>on</i> <i>Prunus cerasifera</i> Ehrhar.</p> <p> <b>Diagnosis.</b> Female. Head in front view lemon yellow with facial part whitish yellow. Occiput yellow with a dark brown band above occipital foramen. Apex of midfemur and base of midtibia (Fig. 6) without peg-like bristles.</p> <p> <b>Description</b>. Female. Body length 1.5mm. Head lemon yellow with facial part whitish yellow; occiput with a dark brown band above occipital foramen; eyes and ocellus dark brown; antenna (Fig. 3) mostly dark brown except scape lemon yellow. Mesosoma mostly lemon yellow except for the following distinctly dark brown parts: pronotum, mesoscutum and axilla (Fig. 8). Fore- and hindwing hyaline. Legs mostly yellow to pale yellow except fore leg (Fig. 5) with dorsal two thirds of tibia dark brown; mid leg (Fig. 6) with distal half or more of coxa darker dorsally; hind leg (Fig. 7) with about basal one thirds of coxa and apices of all tarsi brown. Ovipositor (Fig. 10) dark brown.</p> <p>Head. Head 0.8× as long as wide in frontal view. Frontovertex with numerous brown setae and 0.43× as long as head width. Eyes densely setose, each setae shorter than diameter of a facet; POL 1.83×as long as OOL; ocellus triangle with apical angle obtuse. Mandible with two small teeth and a truncation. Torulus with upper margin below level of lower eye margin.Antenna stout (Fig. 3); scape about 4.5× as long as wide and slightly longer than clava; pedicel 1.27× as long as wide; F1 2× as long as wide, longer than F2 and F3; F2 1.3× as long as wide and longer than F3; F3 1.19× as long as wide; clava 2× as long as wide and about half the lengh of funicle. Relative measurements: HL 22, HW 28 FV 12, POL 5.5, OOL 3, SL 9, SW 2, PL 2.8, PW 2.2, F1L 6, F1W 3, F2L 4, F2W 3, F3L 3.8, F3 W 3.2, CL 8, CW 4.</p> <p>Mesosoma. Dorsum of mesosoma finely reticulate; axilla (Fig. 8) with elongated reticulate sculpture and 2 long setae. Mesoscutum with median area about 0.76× as long as wide. Mesoscutellum (Fig. 8) 1.5× as long as wide with densely setose and lateral with a pair of setae. Fore wing (Fig. 4) 2.2× as long as wide; marginal vien with 19 setae and 1.19× as long as submarginal vien; postmarginal vien distinctly shorter than stigma vein; stigma with sensilla arranged in a line. Hind wing 4.13× as long as wide. Midtibial spur (Fig. 6) slightly shorter than corresponding basitarsus. Relative measurements: SCL 18, SCW 12, FWL 66, FWW 30, SMV 16, MV 19, HWL 54, HWW 13, MT 12.3, MST 4, MBT 4.3.</p> <p>Metasoma. Metasoma about 1.18× as long as mesosoma. Ovipositor (Fig. 10) originating from the base of TIV and 1.22× as long as midtibia; second valvifer 4× as long as third valvula and the latter 0.7× as long as midbasitarsus. Relative measurements: OL 15, SVL 12, TVL 3.</p> <p> <b>Male</b>. Very similar to female except for sexual differences. Moreover the pronotum and axilla of males often dark brown.</p> <p> <b>Variation.</b> The coloration on the dorsum of mesosoma and mesopleuron are variable in females. They can vary from nearly completely dark brown (yellow in the sides of the side lobe, Fig. 1) to almost pale yellow (dark brown in the middle of pronotum, and anterior part of mesoscutum). In males, the posterior part of mesoscutum and mesoscutellum can vary from pale yellow (Fig. 11) to dark brown (Fig. 12).</p> <p> <b>Host.</b> <i>Rhodococcus sariuoni</i> Borchsenius; <i>Eulecanium kuwanai</i> Kanda and <i>Takahashia japonica</i> Cockerell (Hemiptera: Coccidae).</p> <p> <b>Etymology.</b> The specific name refers to its occiput with a dark brown band.</p> <p> <b>Comments.</b> This species had been treated as <i>Coccophagus</i> sp 4 in Zhou <i>et al.</i> (2018), but they did not provide description of this species. Using the key of Hayat (1998) and Li & Chen (2017), the species runs to <i>C. silvestrii</i>, <i>C. chloropulvinariae</i> Hayat and <i>C. tropicanus</i> Sugonjaev and Ren. The females of new species can be easily separated from these species by combination of the following: occiput yellow with a dark brown band above occipital foramen, apex of midfemur and base of midtibia without peg-like brisles, outer plates of ovipositor 2× as long as broad.</p>Published as part of <i>Zhang, Lan-Wei, Hu, Hong-Ying & Zhang, Yan-Zhou, 2023, Two new species of Coccophagus Westwood (Hymenoptera: Aphelinidae) from China, pp. 342-350 in Zootaxa 5258 (3)</i> on pages 343-344, DOI: 10.11646/zootaxa.5258.3.7, <a href="http://zenodo.org/record/7780471">http://zenodo.org/record/7780471</a>
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