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排序方式: 共有1503条查询结果,搜索用时 15 毫秒
1.
G.D. Wignall R.W. Hendricks W.C. Koehler J.S. Lin M.P. Wai E.L. Thomas R.S. Stein 《Polymer》1981,22(7):886-889
A series of small angle neutron scattering measurements on blends of normal polystyrene (PSH) and labelled (deuterated) polystyrene (PSD) have been made with concentrations of PSD from 5 to 50 mol %. It is shown that the single chain form factor of the polymer in bulk can be obtained from a single concentration measurement for any concentration of labelled molecules, providing the molecular weights of the parent and labelled molecules are the same and the molecular weight distributions are narrow. 相似文献
2.
Meng Wai Woo 《Drying Technology》2008,26(1):15-26
Current methods in alleviating the wall deposition problem in spray drying emphasize mainly controlling the stickiness of the drying particles and less attention is placed on the properties of the dryer wall. In this experimental study, the effect of wall surface properties on the deposition mechanism has been investigated. Properties considered in classifying different wall materials were surface energy, roughness, and dielectric properties. The model solution contained sucrose, representing low-molecular-weight sugars commonly encountered in spray drying of fruit and vegetable juices. The effect of wall properties on deposition was explored at different drying rates producing particles of different surface rigidity. Larger surface roughness produced higher deposition fluxes for particles with high impact velocity and moisture. Surface energy and surface roughness were found to have no significant effect for dry rigid particles at the middle and bottom elevation of the drying chamber. However, material with lower surface energy (Teflon) exhibited less deposition for rubbery particles at such elevations. Analysis shows that dielectric wall material (Teflon) tends to enhance deposition of dry particles because of attrition at the surface. Higher wall temperature was found to produce slightly more deposition. The results of this work give a general indication of the effect of wall material on the deposition problem and provide the fundamental understanding for further studies along this line. Proper selection of dryer wall material will provide potential alternatives for reducing the deposition problem. 相似文献
3.
The effect of DC flux on the core loss is examined for the practical range of power and frequency. Relevant core loss equations are derived and applied to an optimization algorithm to determine the minimum core loss at a given ratio of s (DC flux density to AC peak flux density). It has been found that the curves of hysteresis loss density versus the ratio of s exhibit a peak at a critical ratio. Below or above this critical ratio, the loss density decreases drastically. On the other hand, the curves of eddy-current loss density versus the ratio of s exhibits a minimum point at a critical ratio. Below or above this critical ratio, the loss density increases gradually 相似文献
4.
We analyze and numerically study the code-matching logic module that is the central element in a proposed soliton-based ring network system running at peak rates of 100 Gb/s. The proposed network is packet-switched, and fast logic is required to route each packet. That is the function of the code-matching logic module, and four soliton logic gates that can perform fast logic are the key devices in its design. The behavior of the code-matching logic module is governed by a large set of parameters, and we simulate it by varying many of these parameters. The physical effects that occur in these devices and their significance are analyzed. The results indicate that the logic module will work but within a restricted parameter range 相似文献
5.
6.
A new bioglass ceramic with composition of Na2O 12%, CaO 28%, P2O5 10% and SiO2 50% with a high bending strength (120–140 MPa) and compressive strength (600–750 MPa) was studied. The crystallized phases of-Ca2P2P7 and Na2Ca3Si6O16 were determined by X-ray diffraction. Optical microscopy of the material revealed that a very uniform crystal size of about 30 m was obtained with high nucleation frequency. The nucleation and crystallization processes were also investigated. The rat shoulder test showed that the material formed a tight chemical bond with biological texture and had good biocompatibility. 相似文献
7.
Chen -Shen Chang Min -Hsiung Hon Sheng -Jenn Yang 《Journal of Materials Science》1991,26(6):1627-1630
A polycrystalline high-density magnesium fluoride, fabricated into plates or shapes by hot-pressing, exhibits high in-line transmittance from 2.5 to 6.0 m, and single-crystal magnesium fluoride extends from 0.1 to 6.0 m. The ultimate and practical transmittance of hot-pressed magnesium fluoride using intrinsic and extrinsic reflectance, absorptance and scattering mechanisms, are investigated. The intrinsic scattering mechanism due to the polycrystalline structure is basically responsible for the tremendous difference in transmittance in the short wavelength region of the spectrum. The in-line transmittance of polycrystalline and singlecrystal MgF2 is discussed in terms of sample thickness. 相似文献
8.
Feature-based design of progressive press tools 总被引:2,自引:0,他引:2
9.
Liqiao Tian Onyx W. H. Wai Wenbo Li Jian Li Wenkai Li 《International journal of remote sensing》2016,37(14):3400-3413
This study proposed a method for developing high spatial resolution Gaofen-1 satellite (GF-1) Wide Field Imager (WFI)-based total suspended matter concentration (CTSM) retrieval model with the assistance of Moderate Resolution Imaging Spectroradiometer (MODIS) data, using the Deep Bay in China as a case. Based on long-term calibrated CTSM measurements of optical backscatter (OBS) 3A turbidity and temperature monitoring system of two stationary stations from January 2007 through November 2008, 33 match-ups were selected to build an exponential retrieval model for MODIS atmospherically corrected remote-sensing reflectance (Rrs) ratio (Rrs,645/Rrs,555). Validation of the MODIS model showed well agreement with the seven in situ CTSM measurements with a root mean squared error (RMSE) of 5.06 mg l?1 and a coefficient of determination R2 of 0.80. Aided with six MODIS retrieved CTSM products, different band combinations (single band (Rrc,660), band subtraction (Rrc,660–Rrc,560), band ratio (Rrc,660/Rrc,560), and total suspended matter index at 660 nm band (TSMI660) were evaluated for simultaneous GF-1 WFI Rayleigh-corrected reflectance (Rrc). The results showed that the exponential model based on the Rayleigh-corrected reflectance ratio (Rrc,660/Rrc,560) could achieve acceptable accuracy, with RMSE of 14.80 mg l?1 and R2 of 0.62. The proposed method would be helpful for dynamic monitoring in the Deep Bay, and more important could also provide an alternative approach for studies when in situ measurements are unreachable. 相似文献
10.
A simple controller synthesis method is developed for certain classes of linear, time-invariant, multi-input multi-output plants. The number of poles in each entry of these controllers depends on the number of right-half plane plant zeros, and is independent of the number of poles of the plant to be stabilized. Furthermore, these controllers have integral-action so that they achieve asymptotic tracking of step input references with zero steady-state error. The designed controller’s poles and zeros are all in the stable region with the exception of one pole at the origin for the integral-action design requirement. The freedom available in the design parameters may be used for additional performance objectives, although the only goal here is stabilization and tracking of constant references. 相似文献