Numerical Simulation for Dynamic Response of Large Space Cylindrical Reticulated Shell under Internal Explosion by Ritz POD Method

A numerical simulation test of the internal explosive loading on large space structure was carried out by employing algorithm ANSYS/LS DYNA.An appropriate model was established for calculating the dynamic responses of the large space cylindrical reticulated shell under inner blast loading based on the proof of correctness and reliability of the model and parameters selection.Combining the Ritz vibration mode superposition method with the Proper Orthogonal Decomposition (POD) method, the problems of spatiotemporal asynchrony of shock waveforms and pressure distributions on large space structure surface were solved and the calculation for dynamic response of large space structure was reduced and simplified.Furthermore, the numerical simulation of dynamic responses was carried out.And the influence of the ratio of rise to span and the explosive position on the dynamic responses of the structure was studied.It was found that the calculation model was suitable for the dynamic response analysis of the large space cylindrical reticulated shell under internal explosion and the cylindrical reticulated shells with bigger ratios of rise to span were stronger in the capacity of anti explosion.In general, the damages to the large space structure caused by eccentric blast shock waves were more serious than that caused by central explosion.And it was the most disadvantageous to the edge components of the structure.The more attention should be paid to the anti explosion capacity of the support areas and the edge components while designing the shells.     

A Simplified Thermoelastic Model for Composite Iaminated Shells

To effectively analyze the one way coupled thermoelastic problem for composite laminated shells, a simplified thermoelastic shell model based on the variational asymptotic method (VAM) was developed. The 3 D energy functional for composite laminated shell was established according to the Hamilton extended principle. Then the 3 D energy was asymptotic expanded into a series of 2 D approximation energies by taking advantage of the inherent small parameters. Finally, the approximate energy was converted to the form of Reissner Mindlin model, and the 3 D recovery relationships were deduced to accurately predict the 3 D field distribution along the thickness direction. The cylindrical bending example of a four layer composite laminated shells under the sinusoidal surface load and temperature field shows that the modeling speed is fast (equivalent single layer model, which can reduce two or three order calculations compared to the 3 D finite element method), and the nonlinear approximation ability is excellent (convergent to the exact solution).     

食品加工剩余物板栗壳的利用研究进展

为了更好地对食品加工剩余物板栗壳进行开发利用,促进节能减排,综述了国内外最近20年在板栗壳资源化利用方面的研究进展,发现现有研究涉及将板栗壳作为生物吸附剂用于重金属污水处理、作为基质用于食用菌栽培和作为原料用于活性炭制备,以及从中提取天然色素用于食品着色和纺织品印染等方面,但这些研究并不系统,今后还需对板栗壳色素进行安全性评价,补充其毒理学和代谢方面的数据。板栗壳对重金属的吸附量偏低,有待于进一步通过理化改性提高其吸附性能,提取过色素的板栗壳残渣可进一步作为原料用于制备活性炭,以达到循环利用。     

Stresses and Deformations Independent of Polar Angle in Anisotropic Layered Cylindrical Shells

In this paper authors present a method to analyse stresses and deformations independent of polar angle in anisotropic layered cylindrical shells.An ordinary differential equation concerning deflection,its general solution and formula for analyzing stresses and deformation in fiber wind layered cylindrical shells are deduced.     

2种壳色梨形环棱螺贝壳7种金属元素质量分数比较分析

利用电感耦合等离子体质谱(ICP-MS)对梨形环棱螺(Bellamya purificata)青色和紫色贝壳的7种金属元素质量分数进行了比较分析。结果显示,紫色梨形环棱螺贝壳中铁(Fe)、质量分数显著高于青色贝壳。青色贝壳中钾(K)、镁(Mg)、锰(Mn)的含量显著高于紫色贝壳,钠(Na)、锶(Sr)、锌(Zn)元素含量在两种壳色贝壳中差异不显著。贝壳中Fe含量和K、Mg、Mn的含量呈显著负相关,与Sr、Zn含量的相关性不显著。K、Mg、Mn、Na的四种元素含量呈显著正相关。     

Coupled Vibration of Saturated Fractional Derivative Type Viscoelastic Soil of a Circular Tunnel with Partially Sealed Shell Lining

Considering the compression of medium and fluid, coupled vibration of saturated fractional derivative type viscoelastic soil and a circular tunnel with partially sealed shell lining in the frequency domain is investigated according to theories of Biot and elastic shell. The stress and displacement constitutive behavior of the soil skeleton is described by fractional derivative model which reflects the rheological properties of the medium while regarding soil as a liquid-solid saturated porous medium. The expressions of displacement, stress and pore water pressure are obtained while the inner boundary of circular tunnel is subjected to axially symmetric radial traction and axially symmetric fluid pressure respectively by introducing a partially permeable boundary condition. With the parameter analysis, it is revealed that the order of fractional derivative model on the responses for the system subjected to the symmetric radial traction is much greater than that of the system under the axially symmetric fluid pressure. And resonance phenomenon occurs obviously. Nevertheless the system responses do not have remarkable resonance phenomenon under axially symmetric fluid pressure.     

Finite element model of coupled systems for vibration reduction plates with smart constrained layer damping

Considering the relationships of coupling movement and compatible displacement among bonding layer, piezoelectric layer, damping layer, and base structure, a finite element dynamic model of coupled systems for vibration reduction plates is established. The model combined with piezoelectric theory, finite element theory and ADF model of viscoelastic damping material can be suitable for vibration model of complex SCLD structure. The dynamics parameters for clamped-clamped steel plate with partially treated smart constrained layer damping are obtained by theoretical calculation, ANSYS modal analysis and modal experiment. The results show that theoretical values are closer to the test results and ANSYS analysis, and the methods proposed is more accurate and effective.     

花生壳研究现状与应用前景分析

花生是我国的主要油料作物和经济作物,花生壳作为其副产物占花生产量的30%左右,花生壳含有多种矿物质及功能成分,在农业生产、食品加工、功能性产品开发等方面有重要的应用价值。但是,目前由于研究技术受限及研究工艺落后,花生壳大部分仍用作饲料和肥料,附加值与利用率低。文章对花生壳的组成成分及其在农业、食品、医药、环保、化工及建筑方面的重要应用及关键技术进行综述及分析。认为深入开发花生壳是未来花生壳利用的重要方向,今后应以工艺优化及技术提升为主,将目前实验室阶段的研究成果形成大规模生产,真正实现循环农业和低碳经济。     

THE THEORETICAL ANALYSIS OF RADIAL DISPLACEMENT AND COMPATIBLE CONDITIONS OF BOTTOM PLATE OF PISTON FRAME IN LARGE CONTAINER

Taking aecount of shear action between the piston truss the bottom plate, this paper assumes the bottom plate to be a part-ring and supposes that the shear distribution follows the power series law, making the problem to be a problem of mixed boundary condition of part plate. In the paper, the solution of this elastic plane problem is derived. The general expressions of radial displacement of bottom plate are given. The compatible conditions both at the nodes of the lower chord of the truss and at the central cylindrical shell are analyzed.     

Prebuckling Deformation Theory of Filament-Wound Cylindrical Shells

Based on the theory of composite,the analysis of prebuckling deformation of filament-wound cylindrical shells is performed. The prebuckling deformation theory under axial pressure,lateral pressure or liquid pressure is presented.The emphases are placed on the boundary conditions and coupling effect.     

The availability and quality of the mussel prey (Mytilus edulis) of oystercatchers (Haematopus ostralegus)

Spatial variations in the availability and quality of the mussel Mytilus edulis food supply of Oystercatchers Haematopus ostralegus on the Exe estuary, England, are described. Oystercatchers open mussels by stabbing into gaping mussels (or prising open closed ones) or by hammering a hole in either the dorsal or ventral shells. Spatial variations in the food supply are considered at four scales. In decreasing order of size, these are (i) whole mussel beds, (ii) zones within a mussel bed, (iii) different places within one zone, and (iv) different places within one clump of mussels. The first two scales are clearly related to exposure time. Both between and within the 12 main mussel beds of the estuary, most upshore mussels are up to 10% less likely than downshore mussels to be hidden under mud. However, upshore mussels of a given length contain less flesh, have thicker ventral shells and, except on high-level beds subject to wave erosion, have thicker dorsal shells than downshore mussels. Mussels at the top of the shore also contain the highest infestations of the helminth parasite of Oystercatchers, Psilostomum brevicolle. At a particular shore level, mussels of a given length have less flesh and thicker shells, though only on the dorsal side, in areas of high mussel density. Within one clump, mussels of a given length with thick dorsal shells have more flesh than those with thin shells. In contrast, flesh content is slightly higher in mussels that are thin on the ventral side. Flesh content and shell thickness on both sides are unaffected by whether a mussel is visible at the edge of a clump or hidden inside. Simulations with a model of foraging Oystercatchers suggested that variations in mussel availability (visibility and shell thickness) and flesh content at all four scales could sometimes have an important influence on intake rate. Most published values of intake rates of Oystercatchers eating surface-dwelling mussels may be biassed (and often considerably over-estimated) by the erroneous assumption that prey of average flesh content are taken.     

A Study on Vibration Isolation for the Machine on Flexible Foundations

The problem of vibration isolation for the multi supporting machine installed on flexible foundations was studied by power flow and four end parameters methods.The general model of machine,isolator and flexible foundations was founded,and the transmission characteristic of the vibration system is analyzed.The expressions of power flow of the system with wave propagation effect being concerned was also presented.Finally,the effect of foundation flexibility and wave propagation on isolation was analyzed in detail.     

Pressure driven flow of the MR fluids in the cylindrical pipe

Herschel-Bulkley model is used to describe rheological behavior of the Magnetorheological (MR) fluids subject to an applied magnetic field. Based on momentum equation, the effect of the applied magnetic field on the pressure driven flow of the MR fluids in the cylindrical pipe is analyzed theoretically. The expressions for the velocity and the volumetric flow rate in viscoplastic flow are derived to provide a theoretical foundation for the design of cylindrical pipe MR devices. The results indicate the MR fluids have the properties of both viscosity and viscoplasticity. The flow of the MR fluids in the cylindrical pipe exhibits viscoplastic flow behavior. The velocity exhibits the distributions of both parabolic curve and straight line with the magnetic field direction. The volumetric flow rate can be continuously adjusted by an external magnetic field.     

Design of Double Layer Torsional Reticulated Shell Using Back- Propagation Neural Network

In this paper artificial neural networks are used for design of large span double layer torsional reticulated shell. The torsional reticulated shells with spans varying between 50.0 - 80.0m are considered, Back -propagation algorithm is employed for training efficient neural networks for evaluation of the maximum deflection, weight and design of double layer torsional reticulated shell. A special method is developed for data ordering to reduce the nonlinearity of data and to increase the speed of training. This approach also provides the necessary stability. It shows that it is feasible to design double layer reticulated shell with artificial neural networks.     

Preliminary Optimization of Partial Single layer Reticulated Shells Based on Uniform Design[JP]

Size, shape and topology optimizations are involved in the structural design of partial single layer reticulated shells. To meet the requirements of computation efficiency during preliminary design, a uniform design method was adopted to achieve multi level optimization. Only existing software packages for reticulated shells were used in the experiment design. By regressing the computing data, approximate functional relations between the indexes (steel weight, deflections, basic frequency, and minimal nonlinear buckling load) and variables (rise of the shell, single layer area, and design stress ratio for single layer members) were obtained. The best combination of the variables was acquired by solving a simple programming problem. Comparative design of a multipoint supported hexagonal reticulated shell verified the efficiency and reliability of this approach.     

板坯连铸结晶器内凝固坯壳的三维数值模拟

基于流场和温度场的计算,对断面为1 780 mm×225 mm的板坯结晶器进行数值模拟,考虑3种不同水口条件下,钢液流动对凝固壳的冲刷,计算出凝固壳厚度的三维分布特征,并与二维切片法的计算结果进行了对比。结果表明：有水口时结晶器角部位置凝固壳最大值为约45 mm,宽面和窄面中心凝固厚度壳最大值为24 mm,分别比无水口条件下凝固壳薄1~2 mm;钢液的扩散会使凝固壳在距离结晶器角部300 mm和顶部400 mm的位置形成约深度2.5 mm的凹陷;同时钢液会冲刷整个结晶器窄面的凝固壳,在窄面中心最严重;对比不同的水口,凸底水口冲刷最大,凹底最小。     

Physical and biological aspects of shell accumulation on a modern macrotidal flat,Inchon, Korea

Shell beds are comparatively rare on large tidal flats near Inchon, Korea, where barrier islands, well-developed intertidal drainage channels, and landward salt marshes also are absent. Even though landward transport of non-indigenous shells is discernible, most shell accumulations evidently originate through comparatively rapid deposition of sediments coupled with gradual mortality within local populations; individual valves typically experience only minor lateral displacement. Apparent cohort size classes remain distinguishable within some assemblages. Old shells predominate among gastropod assemblages whereas new shells predominate among bivalve assemblages, implying greater rates of productivity among bivalves than among gastropods.     

Spawning of two Pomatoschistus species (gobbidae) in relation to nest availability and depth: A field experiment

The spawning of two sympatric gobiid fishes, the sand goby Pomatoschistus minutus and the common goby Pomatoschistus microps was investigated in relation to nest availability and depth. In two field experiments, carried out in the northern Baltic proper during summer, empty shells of the mussel Mya arenaria were divided into three size groups and provided as spawning substrates. The shells were set out at different depths and at different densities.Spatial habitat partitioning by depth was found. The sand goby preferred the deeper bottoms (2.8 m) and the common goby spawned only in areas shallower than 1 m. The spawning of the two species was separated in time by about 6 weeks with an overlap at the beginning of July. Low water temperatures (∼10°C) in June probably delayed spawning in the common goby.The sand goby preferred the larger shells. The larger the shells, the larger was the number of eggs, i.e. the male potential reproductive success. The common goby preferred the smaller shells, and their potential reproductive success did not show a clear trend with increasing shell size.In both species, the mean number of shells used for spawning increased with increasing substrate density. The maximum nesting density was 21 nests per m² for the sand goby and 20 nests per m² for the common goby. The maximum total density for both species together was 23 nests per m².Interspecific competition for spawning substrates was minimized, as spawning was separated in time and each species preferred different sizes of shell. The intensity of spawning under the shells provided indicates that a lack of suitable substrates limits spawning by both species in this area. The larger sand goby is limited in particular by the lack of larger substrates, and is probably forced to spawn in shallow water when suitable shells do not occur in its preferred depth range.     

ANALYSIS AND PROGRAM FOR CHUNK AND STIFFENED SHELL STRUCTURES BY FINITE ELEMENT METHOD

The improved isoparametric shell element and the biased Isoparametric beam element are applied to the composite structures which consist of cubic chunks and stiffened shells. A flexible and practical method is found for this type of composite structure. The example shows that the theory and program are efficient.     

Clonal selection in 'Uzunmusa' hazelnut

Clonal selection was practised in ‘Uzunmusa’ hazelnut over the past 3 years (1999‐2001) to select the highest quality types. Based on an initial assessment of a total of 102 types, 45 were selected for further study. The best types were selection numbers (SN) 397 and 570. The two selected clones have very good characteristics and seem to be superior to the standard clone. The clones had a higher kernel percentage (62.72%), a higher number of nuts per cluster (5.5), thinner shells (0.75 mm) and heavier nuts (2.34 g). On the other hand, the clones seem to be very suitable for the nut industry because of their oil content and size. These types have very thin shells which are suitable for in‐shell market.