质量上的最高水准与操作上的方便性--RSB-D 35并条工艺

全球范围内的纺纱厂一直面对着以下挑战和要求: ·为了保持竞争力,必须一直有稳定的纱线质量; ·国际性的竞争要求生产成本不断降低;     

Finite strain 3D thermoviscoelastic constitutive model for shape memory polymers

A 3D thermoviscoelastic model is proposed to represent the thermomechanical behavior of shape memory polymers. The model is based on a physical understanding of the material behavior and a mechanical interpretation of the stress–strain–temperature changes observed during thermomechanical loading. The model is thermodynamically motivated and is formulated in a finite strain framework in order to account for large strain deformations. Model predictions capture critical features of shape memory polymer deformation and, in some cases, provide very favorable comparisons with experimental results. POLYM. ENG. SCI. 46:486–492, 2006. © 2006 Society of Plastics Engineers.     

A novel route to a polycrystalline silicon thin-film solar cell

An alternative approach is described for the fabrication of a polycrystalline silicon thin-film solar cell on inexpensive substrates. In a first step amorphous silicon is recrystallized in an aluminum-induced crystallization process forming a large-grained polycrystalline silicon layer on glass or metal substrates. In a second step this layer is used as a template for epitaxial growth of the absorber layer (2–3 μm thick) at T<600 °C using ion-assisted deposition techniques. The third step consists of the formation of an a-Si:H/c-Si heterojunction by depositing an a-Si:H emitter from the gas phase. It will be shown that each of these steps has been successfully developed and can now be implemented in a solar cell process.     

Neutron detection by measuring capture gammas in a calorimetric approach

The neutron capture detector (NCD) is introduced as a novel detection scheme for thermal and epithermal neutrons that could provide large-area neutron counters by using common detector materials and proven technologies. The NCD is based on the fact that neutron captures are usually followed by prompt gamma cascades, where the sum energy of the gammas equals to the total excitation energy of typically 6-9 MeV. This large sum energy is measured in a calorimetric approach and taken as the signature of a neutron capture event. An NCD consists of a neutron converter, comprising of constituents with large elemental neutron capture cross-section like cadmium or gadolinium, which is embedded in common scintillator material. The scintillator must be large and dense enough to absorb with reasonable probability a portion of the sum energy that exceeds the energy of gammas emitted by common (natural, medical, industrial) radiation sources. An energy window, advantageously complemented with a multiplicity filter, then discriminates neutron capture signals against background. The paper presents experimental results obtained at the cold-neutron beam of the BER II research reactor, Helmholtz-Zentrum Berlin, and at other neutron sources with a prototype NCD, consisting of four BGO crystals with embedded cadmium sheets, and with a benchmark configuration consisting of two separate NaI(Tl) detectors. The detector responses are in excellent agreement with predictions of a simulation model developed for optimizing NCD configurations. NCDs could be deployed as neutron detectors in radiation portal monitors (RPMs). Advanced modular scintillation detector systems could even combine neutron and gamma sensitivity with excellent background suppression at minimum overall expense.     

Hormone discharges from a midwest tile-drained agroecosystem receiving animal wastes

Manure is increasingly being viewed as a threat to aquatic ecosystems due to the introduction of natural and synthetic hormones from land application to agricultural fields. In the Midwestern United States, where most agricultural fields are tile-drained, there is little known about hormone release from fields receiving animal wastes. To this end, seven sampling stations (four in subsurface tile drains and three in the receiving ditch network) were installed at a Midwest farm where various types of animal wastes (beef, dairy, and poultry lagoon effluent, dairy solids, and subsurface injection of swine manure) are applied to agricultural fields. Water flow was continuously monitored and samples were collected for hormone analysis during storm events and baseline flow for a 15 month study period. The compounds analyzed included the natural hormones 17α- and 17β-estradiol, estrone, estriol, testosterone, and androstenedione and the synthetic androgens 17α- and 17β-trenbolone and trendione. Hormones were detected in at least 64% of the samples collected at each station, with estrone being detected the most frequently and estriol the least. Testosterone and androstendione were detected more frequently than synthetic androgens, which were detected in fewer than 15% of samples. Hormone concentrations in subsurface tile drains increased during effluent irrigation and storm events. Hormones also appeared to persist over the winter, with increased concentrations coinciding with early thaws and snowmelt from fields amended with manure solids. The highest concentration of synthetic androgens (168 ng/L) observed coincided with a snowmelt. The highest concentrations of hormones in the ditch waters (87 ng/L for total estrogens and 52 ng/L for natural androgens) were observed in June, which coincides with the early life stage development period of many aquatic species in the Midwest.     

Point cloud reconstruction with sub-pixel accuracy by slice-adaptive thresholding of X-ray computed tomography images

We present a methodology for the calculation of highly accurate point clouds from an image stack obtained with a two-dimensional industrial X-ray computed tomography scanner. The basic idea is to apply a different threshold value to each computed tomography image, which is then used for the calculation of the point cloud. A dense and smooth cloud can be obtained by interpolating the grey values between pixles. Our method combines both. An easy to implement thresholding algorithm is used for the estimation of a slice-by-slice threshold and an interpolating algorithm to reconstruct highly accurate point clouds.It is shown that the point clouds approximate the true dimensions of a scanned part with sub-pixel accuracy.     

信号路径设计

每当我们设计高速的混合信号系统时,我们最好先审视信号路径的每一环节,详细评估各区块的信号失真程度.本文主要介绍输入或接收器路径的设计.发送器或输出路径的设计将会留待以后再详细介绍.典型的接收器或仪表测量系统由信号传感器、模拟信号处理区块、数据转换器、接口及数字处理区块等多个不同环节组成(参看图1).但本文只集中讨论输入路径设计的模拟及混合信号部分.我们必须小心挑选信号路径的各个区块,才可取得预期的成效.